Nonmelanoma skin cancer in relation to ionizing radiation exposure among U.S. radiologic technologists

Ionizing radiation (IR) is an established cause of nonmelanoma skin cancer, but there is uncertainty about the risk associated with chronic occupational exposure to IR and how it is influenced by ultraviolet radiation (UVR) exposure. We studied 1,355 incident cases with basal cell carcinoma (BCC) and 270 with squamous cell carcinoma (SCC) of the skin in a cohort of 65,304 U.S. white radiologic technologists who responded to the baseline questionnaire survey in 1983-1989 and the follow-up survey in 1994-1998. Cox's proportional-hazards model was used to estimate relative risks of BCC and SCC associated with surrogate measures of occupational exposure to IR and residential UVR exposure during childhood and adulthood, adjusted for potential confounders including pigmentation characteristics. Relative risks of BCC, but not of SCC, were elevated among technologists who first worked during the 1950s (RR = 1.42; 95% CI = 1.12-1.80), 1940s (RR = 2.04; 95% CI = 1.44-2.88) and before 1940 (RR = 2.16; 95% CI = 1.14-4.09), when IR exposures were high, compared to those who first worked after 1960 (p for trend < 0.01). The effect of year first worked on BCC risk was not modified by UVR exposure, but was significantly stronger among individuals with lighter compared to darker eye and hair color (p = 0.013 and 0.027, respectively). This study provides some evidence that chronic occupational exposure to IR at low to moderate levels can increase the risk of BCC, and that this risk may be modified by pigmentation characteristics.     

Lung cancer risk among US radiologic technologists, 1983-1998

While exposure to moderate to high-dose ionizing radiation is an established risk factor for lung cancer, the relationship between lung cancer and chronic low dose radiation remains uncertain. We examined lung cancer risk among 71,894 US radiologic technologists who were certified during 1926-1982, responded to a baseline questionnaire (1983-1989), and were free of cancer other than non-melanoma skin cancer at baseline. Study participants were followed until completion of a second questionnaire (1994-1998), death, or August 31, 1998. We identified 287 lung cancer cases: 66 incident cases and 221 decedents. Exposure to radiation was inferred based on work history information provided in the baseline questionnaire. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazard models adjusted for age, race/ethnicity and smoking. Smoking-adjusted lung cancer risk was not related to working as a radiologic technologist in early years when radiation exposures were likely highest (RR = 0.9; 95% CI, 0.5-1.8 for year first worked before 1940 compared to year first worked >or=1960), nor was risk related to the year first worked after 1940 or the number of years worked in any decade. While lung cancer risk was increased in radiologic technologists who held patients for X-rays, or who allowed others to take numerous practice X-rays on them, the trend was not statistically significant in either case. Although we adjusted for smoking, the possibility of residual confounding exists. Overall, we find very limited evidence that chronic low-to-moderate dose occupational exposure increased lung cancer risk in the US Radiologic Technologist cohort.     

Breast cancer mortality among female radiologic technologists in the United States

We evaluated breast cancer mortality through 1997 among 69 525 female radiologic technologists who were certified in the United States from 1926 through 1982 and who responded to our questionnaire. Risk of breast cancer mortality was examined according to work history and practices and was adjusted for known risk factors. Breast cancer mortality risk was highest among women who were first employed as radiologic technologists prior to 1940 (relative risk [RR] = 2.92, 95% confidence interval [CI] = 1.22 to 7.00) compared with risk of those first employed in 1960 or later and declined with more recent calendar year of first employment (P for trend =.002). Breast cancer mortality risk increased with increasing number of years of employment as a technologist prior to 1950 (P for trend =.018). However, risk was not associated with the total number of years a woman worked as a technologist. Technologists who first performed fluoroscopy (RR = 1.69, 95% CI = 1.02 to 3.11) and multifilm procedures (RR = 1.87, 95% CI = 1.04 to 3.34) before 1950 had statistically significantly elevated risks compared with technologists who first performed these procedures in 1960 or later. The high risks of breast cancer mortality for women exposed to occupational radiation prior to 1950 and the subsequent decline in risk are consistent with the dramatic reduction in recommended radiation exposure limits over time.     

Breast cancer incidence in U.S. radiologic technologists

BACKGROUND: Studies of atomic bomb survivors and medically exposed populations have demonstrated an increased risk of breast cancer associated with acute or protracted, intermediate-dose or high-dose, ionizing radiation; however, the risks associated with low-dose and low-dose-rate (protracted) exposures are less certain. METHODS: The authors evaluated incident breast cancer risks from 1983 to 1998 according to employment characteristics and a 4-level proxy index for cumulative radiation exposure based on 2 mail surveys among 56,436 U.S. female radiologic technologists who were certified from 1925 to 1980, adjusting for established breast cancer risk factors. RESULTS: During follow-up, 1050 new breast cancer diagnoses were ascertained. Compared with radiologic technologists who began working in 1970 or later, adjusted breast cancer risks for those who first worked in the 1960s, 1950s, 1940s, from 1935 to 1939, and before 1935 were 1.0 (95% confidence interval [CI], 0.8-1.2), 1.2 (95% CI, 0.9-1.6), 1.0 (95% CI, 0.7-1.5), 1.8 (95% CI, 1.0-3.2), and 2.9 (95% CI, 1.3-6.2), respectively. The risk rose with the number of years worked before 1940 (P value for trend = .002) and was elevated significantly among those who began working before age 17 years (relative risk, 2.6; 95% CI, 1.3-5.1; 10 women) but was not related to the total years worked in the 1940s or later. Compared with technologists who had a Level 1 (minimal) proxy index for cumulative radiation exposure, breast cancer risks were 1.0 (95% CI, 0.9-1.2), 1.0 (95% CI, 0.7-1.3), and 1.5 (95% CI, 1.0-2.2), respectively, for technologists who had Level 2, Level 3, and Level 4 (highest) exposure. CONCLUSIONS: Breast cancer risk was elevated significantly in female radiologic technologists who experienced daily low-dose radiation exposures over several years that potentially resulted in appreciable cumulative exposure. The increased risk for total years worked before 1940, but not later, was consistent with decreasing occupational radiation exposures, improvements in radiation technology, and more stringent radiation protection standards over time.     

Cancer and other causes of mortality among radiologic technologists in the United States

Data are limited on the role of chronic exposure to low-dose ionizing radiation in the etiology of cancer. In a nationwide cohort of 146,022 U.S. radiologic technologists (73% female), we evaluated mortality risks in relation to work characteristics. Standardized mortality ratios (SMRs) were computed to compare mortality in the total cohort vs. the general population of the United States. Mortality risks were low for all causes (SMR = 0.76) and for all cancers (SMR = 0.82) among the radiologic technologists. We also calculated relative risks (RR) for the 90,305 technologists who responded to a baseline mailed questionnaire, using Poisson regression models, adjusted for known risk factors. Risks were higher for all cancers (RR = 1.28, 95% confidence interval [CI] = 0.93-1.69) and breast cancer (RR = 2.92, 95% CI = 1.22-7.00) among radiologic technologists first employed prior to 1940 compared to those first employed in 1960 or later, and risks declined with more recent calendar year of first employment (p-trend = 0.04 and 0.002, respectively), irrespective of employment duration. Risk for the combined category of acute lymphocytic, acute myeloid and chronic myeloid leukemias was increased among those first employed prior to 1950 (RR = 1.64, 95% CI = 0.42-6.31) compared to those first employed in 1950 or later. Risks rose for breast cancer (p-trend = 0.018) and for acute lymphocytic, acute myeloid and chronic myeloid leukemias (p-trend = 0.05) with increasing duration of employment as a radiologic technologist prior to 1950. The elevated mortality risks for breast cancer and for the combined group of acute lymphocytic, acute myeloid and chronic myeloid leukemias are consistent with a radiation etiology given greater occupational exposures to ionizing radiation prior to 1950 than in more recent times.     

Thyroid cancer and employment as a radiologic technologist

The association between chronic occupational ionizing radiation exposure in the medical field and thyroid cancer is not well characterized. Thyroid cancer incidence was ascertained for 2 periods in a cohort of radiologic technologists certified for a minimum 2 years and enumerated in 1983: (i) cases identified prospectively in 73,080 radiologic technologists who were free of thyroid cancer at the baseline survey and completed a second questionnaire a decade later (N = 121), and (ii) cases occurring prior to cohort enumeration among 90,245 technologists who completed the baseline survey and were thyroid cancer free 2 years after certification (N = 148). Survival analyses estimated risks associated with employment as a radiologic technologist, including duration of employment, period of employment, types of procedures and work practices. The only occupational history characteristic associated with prospectively identified thyroid cancer was a history of holding patients for X-ray procedures at least 50 times (HR = 1.47, 95% CI = 1.01-2.15). Total years worked as a radiologic technologist, years performing diagnostic, therapeutic, and nuclear medicine procedures, employment under age 20 and calendar period of first employment were not associated with thyroid cancer risk. Risk of thyroid cancers diagnosed before the baseline questionnaire was inversely associated with decade first employed as a technologist, and was elevated, albeit imprecisely, among those working more than 5 years prior to 1950 (HR = 3.04, 95% CI = 1.01-10.78). These data provide modest evidence of an association between employment as a radiologic technologist and thyroid cancer risk; however, the findings require confirmation with more accurate exposure models.     

Cancer incidence among medical diagnostic X-ray workers in China, 1950 to 1985

A second follow-up of 27,011 diagnostic X-ray workers in China revealed a 21% greater incidence of cancer than expected based on the experience of 25,782 physicians who did not routinely use X-rays (RR = 1.21; 95% Cl: 1.08 to 1.35). This risk is lower than the 50% excess reported previously and reflects, in part, the reduced risk among workers first employed after 1965, when hospital exposures to radiation probably were lower than in earlier years. The X-ray workers were employed between 1950 and 1985 and followed for an average of 16.1 years. Significantly elevated risks were seen for leukemia (RR = 2.4, n = 34 cases), and cancers of the esophagus (RR = 5.2, n = 19), liver (RR = 1.8, n = 65), and skin (RR = 2.8, n = 9). Cancers of the breast (RR = 1.5, n = 20), thyroid (RR = 1.7, n = 8), and bone (RR = 7.6, n = 4) also occurred more often than expected. Non-significant deficits were observed for cancers of the oral cavity and pharynx (RR = 0.6, n = 16), colon and rectum (RR = 0.8, n = 20), stomach (RR = 0.8, n = 36), and lung (RR = 0.9, n = 45). Excess risks for leukemia and esophageal cancer were seen among men but not among women. The RR for leukemia was higher for X-ray workers who began employment before 1970 than for those who started more recently and also for those who were young when employment began. The patterns of risk associated with duration of work, and with age and calendar time of initial employment, suggest that the excesses of leukemia and skin cancer, and, possibly, cancers of the breast and thyroid, were due to occupational exposure to X-rays. However, there was little evidence that radiation contributed to the increased occurrences of liver or esophageal cancers.     

Sun exposure and interaction with family history in risk of melanoma, Queensland, Australia.

Sun exposure is the main environmental risk factor for melanoma, but the timing of exposure during life that confers increased risk is controversial. Here we provide the first report of the association between lifetime and age-specific cumulative ultraviolet exposure and cutaneous melanoma in Queensland, Australia, an area of high solar radiation, and examine the association separately for families at high, intermediate and low familial melanoma risk. Subjects were a population-based sample of melanoma cases diagnosed and registered in Queensland between 1982 and 1990 and their relatives. The analysis included 1,263 cases and relatives with confirmed cutaneous melanoma and 3,111 first-degree relatives without melanoma as controls. Data on lifetime residence and sun exposure, family history and other melanoma risk factors were collected by a mailed questionnaire. Using conditional multiple logistic regression with stratification by family, cumulative sun exposure in childhood and in adulthood after age 20 was significantly associated with melanoma, with estimated relative risks of 1.15 per 5,000 minimal erythemal doses (MEDs) from age 5 to 12 years, and 1.52 per 5 MEDs/day from age 20. There was no association with sun exposure in families at high familial melanoma risk. History of nonmelanoma skin cancer (relative risk [RR] = 1.26) and multiple sunburns (RR = 1.31) were significant risk factors. These findings indicate that sun exposure in childhood and in adulthood are important determinants of melanoma but not in those rare families with high melanoma susceptibility, in which genetic factors are likely to be more important.     

Occupational risk factors, ultraviolet radiation, and ocular melanoma: a case–control study in France

Background: Ultraviolet radiation has been suspected as a possible cause of ocular melanoma. Because this association is controversial, we examine the role of occupational exposure to ultraviolet radiation on the occurrence of this rare cancer. Material and methods: A population-based case–control study was conducted in 10 French administrative areas (départements). Cases were 50 patients with uveal melanoma diagnosed in 1995–1996. Controls were selected at random from electoral rolls, after stratification for age, gender, and area. Among 630 selected persons, 479 (76%) were interviewed. Data on personal characteristics, occupational history, and detailed information on each job held were obtained from face-to-face interviews using a standardized questionnaire. Estimates of occupational exposure to solar and artificial ultraviolet light were made using a job exposure matrix. Results: Results show elevated risks of ocular melanoma for people with light eye color, light skin color, and for subjects with several eye burns. The analysis based on the job exposure matrix showed a significantly increased risk of ocular melanoma in occupational groups exposed to artificial ultraviolet radiation, but not in outdoor occupational groups exposed to sunlight. An elevated risk of ocular melanoma was seen among welders (odds ratio = 7.3; 95% confidence interval = 2.6–20.1 for men), and a dose–response relationship with job duration was observed. The study also showed increased risk of ocular melanoma among male cooks, and among female metal workers and material handling operators. Conclusion: Following the present study, the existence of an excess risk of ocular melanoma in welders may now be considered as established. Exposure to ultraviolet light is a likely causal agent, but a possible role of other exposures in the welding processes should not be overlooked.     

Brain tumor mortality risk among men with electrical and electronics jobs: a case-control study

Brain tumor risk associated with electrical and electronics jobs and with occupational exposure to microwave and radiofrequency (MW/RF) electromagnetic radiation was evaluated with the use of data from a death certificate-based case-control study of brain tumors and occupational risk factors in northern New Jersey, Philadelphia, PA, and southern Louisiana. Next-of-kin of 435 white men who died of a primary brain tumor and of 386 controls who died from other causes were interviewed to obtain information on lifetime occupational history and other factors that might be related to excess brain tumor risk. The relative risk (RR) for all brain tumors was elevated among men exposed to MW/RF radiation [RR = 1.6; 95% confidence interval (Cl) = 1.0, 2.4] and was significantly elevated among men exposed for 20 or more years. All of the excess risk for MW/RF radiation-exposed subjects was derived from jobs that involved the design, manufacture, repair, or installation of electrical or electronic equipment (RR = 2.3; 95% Cl = 1.3, 4.2), while risk of brain tumors among MW/RF radiation-exposed subjects who never worked in electrical or electronics jobs was not elevated (RR = 1.0; 95% Cl = 0.5, 1.9). Furthermore, risk was elevated for electronics workers who were considered to have no exposure to MW/RF radiation. Among electrical and electronics workers, risk was highest for engineers, teachers, technicians, repairers, and assemblers combined (RR = 3.9; 95% Cl = 1.6, 9.9) and was limited to excess risk from astrocytic tumors (RR = 4.6; 95% Cl = 1.9, 12.2). Risk of astrocytic tumors among these electronics manufacture and repair workers increased with duration of exposure to tenfold among those employed for 20 or more years. Among electricians and power and telephone linemen combined (electrical tradesmen), the RR for astrocytic tumors was slightly elevated, but not statistically significant (RR = 1.8), and showed no consistent evidence of a duration-response relationship. Electrical tradesmen are exposed to extremely low frequency electromagnetic radiation, while men in some jobs associated with electronics manufacture and repair are exposed to electromagnetic radiation in the very high frequency and ultra-high frequency ranges and also may be exposed to soldering fumes, solvents, and a variety of other chemicals.     

Cancer incidence in the US radiologic technologists health study, 1983-1998

BACKGROUND: Workers exposed to low doses of radiation can provide information regarding cancer risks that are of public concern. However, characterizing risk at low doses requires large populations and ideally should include a large proportion of women, both of which rarely are available. METHODS: Among 90305 radiologic technologists in the U.S. (77% women) who were followed during 1983-1998, data concerning incident cancer occurrence was obtained from mailed questionnaires and from death records. Standardized incidence ratios (SIRs) were computed using age-specific, gender-specific, race-specific, and calendar year-specific cancer rates from the Surveillance, Epidemiology, and End Results Program. RESULTS: The SIR for all cancers in both genders combined was 1.04 (95% confidence interval [95% CI], 1.00-1.07; n = 3292 technologists). Female technologists had an elevated risk for all solid tumors combined (SIR = 1.06; 95% CI, 1.02-1.10; n = 2168 women) and for breast cancers (SIR = 1.16; 95% CI, 1.09-1.23; n = 970 women), melanoma (SIR = 1.66; 95% CI, 1.43-1.89; n = 181 women), and thyroid cancers (SIR = 1.54; 95% CI, 1.24-1.83; n = 107 women). Male technologists experienced a decreased risk for solid tumors (SIR = 0.92; 95% CI, 0.85-0.98; n = 755 men); however, melanoma (SIR = 1.39; 95% CI, 1.00-1.79; n = 56 men) and thyroid cancers (SIR = 2.23; 95% CI, 1.29-3.59; n = 17 men) were increased. Among both genders, the risks were decreased for buccal cavity/pharyngeal cancers (SIR = 0.73; 95% CI, 0.55-0.90; n = 54 technologists), rectal cancers (SIR = 0.62; 95% CI 0.48-0.76; n = 53 technologists), and lung cancers (SIR = 0.77, 95% CI, 0.70-0.85; n = 307 technologists). CONCLUSIONS: The elevated risk for breast cancer may have been related to occupational radiation exposure. The observed excesses of melanoma and thyroid cancers may reflect, at least in part, earlier detection among medical workers with easy access to health care.     

A health survey of radiologic technologists.

A health survey of more than 143,000 radiologic technologists is described. The population was identified from the 1982 computerized files of the American Registry of Radiologic Technologists, which was established in 1926. Inactive members were traced to obtain current addresses or death notifications. More than 6000 technologists were reported to have died. For all registrants who were alive when located, a detailed 16-page questionnaire was sent, covering occupational histories, medical conditions, and other personal and lifestyle characteristics. Nonrespondents were contacted by telephone to complete an abbreviated questionnaire. More than 104,000 responses were obtained. The overall response rate was 79%. Most technologists were female (76%), white (93%), and employed for an average of 12 years; 37% attended college, and approximately 50% never smoked cigarettes. Radiation exposure information was sought from employer records and commercial dosimetry companies. Technologists employed for the longest times had the highest estimated cumulative exposures, with approximately 9% with exposures greater than 5 cGy. There was a high correlation between cumulative occupational exposure and personal exposure to medical radiographs, related, in part, to the association of both factors with attained age. It is interesting that 10% of all technologists allowed others to practice taking radiographs on them during their training. Nearly 4% of the respondents reported having some type of cancer, mainly of the skin (1517), breast (665), and cervix (726). Prospective surveys will monitor cancer mortality rates through use of the National Death Index and cancer incidence through periodic mailings of questionnaires. This is the only occupational study of radiation employees who are primarily women and should provide new information on the possible risks associated with relatively low levels of exposure.     

Cancer among medical diagnostic x-ray workers in China

Cancer incidence among 27,011 diagnostic x-ray workers was compared to that of 25,782 other medical specialists employed between 1950 and 1980 in China. X-ray workers had a 50% higher risk of developing cancer than the other specialists [relative risk (RR) = 1.5; 95% CI = 1.3-1.7]. Leukemia was strongly linked to radiation work (RR = 3.5, n = 30). Cancers of the breast (RR = 1.4, n = 11), thyroid (RR = 2.1, n = 7), and skin (RR = 1.5, n = 6) were increased among x-ray workers employed for 10 or more years. High risks of cancers of the esophagus (RR = 3.5, n = 15) and liver (RR = 2.4, n = 48) were not consistent with a radiation effect since risk did not vary by duration of employment. This finding suggested that some differences might exist between groups of hospital workers in social class, alcohol intake, dietary habits, and other risk factors. No excess lung cancer (RR = 0.9, n = 22) or multiple myeloma (n = 0) was observed. Significant excesses of leukemia and cancers of the breast and thyroid occurred among x-ray workers first employed prior to 1960 when radiation exposures in China were high. In fact, it was not uncommon for employees to be given time off from x-ray work because their wbc count was severely depressed. These data indicated that repeated exposure to x-rays over many years can increase the risk of leukemia and several other tumors but apparently not that of lung cancer.     

Air pollution and lung cancer mortality in the vicinity of a nonferrous metal smelter in Sweden

To evaluate the importance of exposure to ambient air pollution for lung cancer risk, we conducted a case-control study in the vicinity of a nonferrous metal smelter. The smelter started operations in 1930 and had very high emissions during the early decades, particularly of arsenic and SO(2). Among subjects deceased 1961-1990 in the municipality where the smelter is located and who had not worked at the smelter, 209 male and 107 female lung cancer cases were identified and matched by sex and year of birth to 518 and 209 controls, respectively. Information on smoking habits, occupations and residences was collected by questionnaire to next-of-kin and from registry data. Living close to the smelter was associated with a relative risk (RR) for lung cancer of 1.38 [95% confidence interval (CI) 0.89-2.14] among men, adjusted for smoking and occupational exposures. No clear difference in risk was detected for men deceased 1961-1979 compared to men deceased 1980-1990 (RR point estimates 1.42 and 1.29, respectively). There appeared to be an increased risk especially for men exposed in the beginning of the operations (RR = 1.51, 95% CI 0.90-2.54), in particular combined with exposure duration shorter than 20 years (RR = 2.52, 95% CI 0.89-7.11). For women, however, no overall increased risk for lung cancer was observed. Although not significant, our findings thus indicated an increased risk of lung cancer among men living close to the nonferrous smelter. This increase appeared to concern primarily men exposed during the early years of operations, when emissions were very high.     

Second cancers following radiation treatment for cervical cancer. An international collaboration among cancer registries

The numbers of second cancers among 182,040 women treated for cervical cancer that were reported to 15 cancer registries in 8 countries were compared to the numbers expected had the same risk prevailed as in the general population. A small 9% excess of second cancers (5,146 observed vs. 4,736 expected) occurred 1 or more years after treatment. Large radiation doses experienced by 82,616 women did not dramatically alter their risk of developing a second cancer; at most, about 162 of 3,324 second cancers (approximately equal to 5%) could be attributed to radiation. The relative risk (RR = 1.1) for developing cancer in organs close to the cervix that had received high radiation exposures--most notably, the bladder, rectum, uterine corpus, ovary, small intestine, bone, and connective tissue--and for developing multiple myeloma increased with time since treatment. No similar increase was seen for 99,424 women not treated with radiation. Only a slight excess of acute and non-lymphocytic leukemia was found among irradiated women (RR = 1.3), and substantially fewer cases were observed than expected on the basis of current radiation risk estimates. The small risk of leukemia may be associated with low doses of radiation absorbed by the bone marrow outside the pelvis, inasmuch as the marrow in the pelvis may have been destroyed or rendered inactive by very large radiotherapy exposures. There was little evidence of a radiation effect for cancers of the stomach, colon, liver, and gallbladder, for melanoma and other skin cancers, or for chronic lymphocytic leukemia despite substantial exposures. An excess of thyroid cancer possibly was related to the low dose received by this organ. Ovarian damage caused by radiation may have been responsible for a low breast cancer risk (RR = 0.7), which was evident even among postmenopausal women. A substantial excess of lung cancer (RR = 3.7) largely may be due to misclassification of metastases and the confounding influence of cigarette smoking. Women who were under 30 or over 50 years of age when irradiated were at greatest absolute risk for developing a second cancer. The RR, however, was higher among those under age 30 years at exposure (RR = 3.9) than among older women. The expression period for radiation-induced solid tumors appeared to continue to the end of life.     

Seroreactivity to epidermodysplasia verruciformis-related human papillomavirus types is associated with nonmelanoma skin cancer

DNA from epidermodysplasia verruciformis-related human papillomavirus (EV-HPV) types is frequently found in nonmelanoma skin cancer (squamous and basal cell carcinoma). Epidemiological studies that investigate the relation between EV-HPV infection and nonmelanoma skin cancer are scarce. We designed a case-control study in which we looked for HPV infection in 540 cases with a history of skin cancer and 333 controls. By measuring seroreactivity to L1 virus-like particles of EV-HPV types 5, 8, 15, 20, 24, and 38 and the genital type HPV16 and by estimating the skin cancer relative risk among HPV seropositives, we analyzed whether EV-HPV serorecognition is associated with nonmelanoma skin cancer. Seroreactivity to five of the six EV-HPV types tested (HPV5, 8, 15, 20, and 24) was significantly increased in the squamous cell carcinoma cases. After adjusting for age and sex, the estimated squamous cell carcinoma relative risk was significantly increased in HPV8 and HPV38 seropositives [odds ratio (OR) = 14.7 (95% confidence interval (CI), 1.6-135) and OR = 3.0 (95% CI, 1.1-8.4), respectively]. The estimated relative risk for nodular and superficial multifocal basal cell carcinoma was also significantly increased in the HPV8 seropositives [OR = 9.2 (95% CI, 1.1-78.2) and OR = 17.3 (95% CI, 2.1-143), respectively] and in the HPV20 seropositives [OR = 3.2 (95% CI 1.3-7.9) and OR = 3.4 (95% CI 1.2-9.5), respectively]. The relative risk of developing malignant melanoma was not increased among HPV seropositives, and no associations were found for HPV16. Restricted analyses among the HPV seropositives only, to exclude distortion by interindividual differences in seroresponsiveness, underscored the significance of our findings. Restricted analyses among patients with skin cancer only, however, revealed that EV-HPV seropositivity was not significantly more present in patients with nonmelanoma skin cancer than in those with melanoma skin cancer. Taken together, our results indicate that EV-HPV serorecognition is nonspecifically associated with nonmelanoma skin cancer and suggest that EV-HPV-directed seroresponses are induced upon skin cancer formation, rather than upon infection.     

A case-control study of melanomas of the soles and palms (Australia and Scotland)

Objectives: Because the factors that influence risk of acral melanomas on the soles and palms in White populations are unknown, we investigated these in a multi-center case-control study.Methods: Cases of melanoma of the feet and hands diagnosed from 1987–93 in persons aged over 18 years were ascertained in eastern Australia and western Scotland. There were 275 cases of melanoma on the soles and palms matched to 496 controls (selected from the electoral roll) in Australia, and 36 cases matched to 72 controls (nominated by general practitioners) in Scotland.Results: Acral melanoma was strongly associated with high total body nevus counts (adjusted relative risk [RR]=6.3, 95% confidence interval [CI]=2.5–15.6), and with nevi on the soles (RR=7.5, CI=3.0–18.6). There were also significant positive associations with a penetrative injury of the feet or hands (RR=5.0, CI=3.0–8.6) and with heavy exposure to agricultural chemicals (RR=3.6, CI=1.5–8.3). Sun-sensitive complexions, cumulative sun exposure and a past history of nonmelanoma skin cancer were also associated with increased risk of acral melanoma. Current cigarette smoking was inversely related to acral melanoma (RR=0.6, CI=0.4–0.9).Conclusions: Melanomas of the soles and palms resemble other cutaneous melanomas in their association with sun exposure, but are distinguished from them by their strong positive associations with nevi on the soles, previous penetrative injury, and exposure to agricultural chemicals, and by their inverse association with smoking.     

The Danish case-control study of cutaneous malignant melanoma. II. Importance of UV-light exposure

A population-based case-control study of 474 patients with cutaneous malignant melanoma and 926 population controls, conducted in East Denmark over a 3-year period, included an evaluation of the relationship of UV-light exposure to cutaneous melanoma risk. Patients with lentigo maligna melanoma were not included. Significantly increased risk was associated with severe sunburn before age 15 (RR = 2.7 for 5 + vs. never), sunbathing (RR = 1.6), boating (RR = 1.4) and vacations spent in the sun (RR = 1.4 for very sunny vs. never). A significant decrease in risk was associated with occupational exposure during the summer in males (RR = 0.7), and no association with cutaneous microtopography was seen. These findings were independent of the effects of constitutional risk factors (naevi, freckles and light hair colour). No association was found between the risk of cutaneous melanoma and exposure to artificial UV-light (fluorescent light, sun lamps, or sun beds). No significant difference was found between superficial spreading melanoma and nodular melanoma with regard to any of the sun exposure variables. Our data indicate that exposure to intermittent intense sunlight is an important risk factor for cutaneous malignant melanoma, while long-term continuous exposure does not appear to be risk factor.     

Multiple myeloma and diesel and other occupational exposures in swedish construction workers

We examined the relationships between occupational exposures and the risk of multiple myeloma among male construction workers in Sweden. A total of 446 myeloma subjects were identified among 365,424 male workers followed from 1971 to 1999. Occupational exposure was assessed using a semiquantitative job-exposure matrix, based on a survey carried out by the Construction Industry's Organization for Working Environment, Occupational Safety and Health in Sweden. Rate ratios (RRs) in the exposed groups relative to the unexposed groups were estimated by Poisson regression. We found an increased risk (RR = 1.3, 95% CI 1.04-1.71) among construction workers exposed to diesel exhaust. Adjustment for other occupational exposures did not change this estimate (RR = 1.3, 95% CI 1.00-1.77). However, there was no monotonic increase in risk with estimated level of exposure (RR for low = 1.4, moderate = 1.1, high = 1.4). There was no evidence of increased risk associated with the other occupational exposures among these construction workers, including asbestos, asphalt, cement dust, metal dust, mineral wool, organic solvents, stone dust and wood dust. Occupational exposure to diesel exhaust in the Swedish construction industry may present a small risk of multiple myeloma, but lack of an exposure-response trend tempers our ability to draw clear conclusions.     

Nested Case-control Study of Occupational Radiation Exposure and Breast and Esophagus Cancer Risk among Medical Diagnostic X Ray Workers in Jiangsu of China

Medical diagnostic X-ray workers are one occupational group that expose to the long-term low-dose externalradiation over their working lifetime, and they may under risk of different cancers. This study aims to determinethe relationship between the occupational X-ray radiation exposure and cancer risk among these workers inJiangsu, China. We conducted Nested case-control study to investigate the occupational X-ray radiation exposureand cancer risk. Data were collected through self-administered questionnaire, which includes but not limitsto demographic data, personal behaviors and family history of cancer. Retrospective dose reconstruction wasconducted to estimate the cumulative doses of the x-ray workers. Inferential statistics, t-test and 2 tests wereused to compare the differences between each group. We used the logistic regression model to calculate the oddsratio (OR) and 95% confidence interval (CI) of cancer by adjusting the age, gender. All 34 breast cancer casesand 45 esophageal cancer cases that detected in a cohort conducted among health workers between 1950~2011were included in this presented study, and 158 cancer-free controls were selected by frequency-matched (1:2).Our study found that the occupational radiation exposure was associated with a significantly increased cancerrisk compared with the control, especially in breast cancer and esophageal cancer (adjusted OR=2.90, 95% CI:1.19-7.04 for breast cancer; OR=4.19, 95% CI: 1.87-9.38 for esophageal cancer, and OR=3.43, 95% CI: 1.92-6.12for total cancer, respectively). The occupational X-ray radiation exposure was associated with increasing cancerrisk, which indicates that proper intervention and prevention strategies may be needed in order to bring downthe occupational cancer risk.