Trends in colorectal incidence by anatomic subsite from 1985 to 2005: a population-based study

Background

Conflicting results on the shift of right–left ratio in colon cancer incidence have been reported. We examine incidence trends by subsite in a population-based study.

Materials and methods

Colorectal cancer cases diagnosed in the 1985–2005 period were identified through the Tuscany Cancer Registry. Colon subsite was defined as proximal and distal; gender, age at diagnosis, histology, and stage were analyzed. Average annual incidence and age-specific rates according to subsite were calculated.

Results

A total of 21,160 colorectal cancer cases were extracted; in 18,311 cases, the subsite was identified: 6,916 rectal, 5,239 proximal, and 6,156 distal. A larger proportion of distal colon cancers presented as early stage when compared with proximal. Incidence of rectal and distal colon cancer remained stable, while proximal colon cancer incidence increased.

Conclusions

Proximal colon cancer incidence rate increased through the period. Temporal variations in the incidence rate by subsite could suggest different carcinogenic pathways of right- and left-sided colon cancer.     

Subsite distribution and incidence of colorectal cancer in New Zealand, 1974–1983

The purpose of this study was to examine changes in subsite distribution and incidence of colorectal cancer within different age groups. Registration of colorectal cancer by the National Cancer Registry of New Zealand approached 100 percent by 1974. The present study was based on 15,395 individuals aged 25 years and over and registered for colorectal cancer between 1974 and 1983. Subsite distribution (right colon, left colon, rectum) for different age groups (25–49, 50–69, 70+ years) was significantly skewed, with an excess of right colonic cancer in individuals aged 25–49 years and 70+ years. This right colonic excess was accompanied by a relative reduction in left colonic cancer. Age adjusted incidence rates for the periods 1974–78 and 1979–83 were compared and stratified by age group and subsite. Incidence rates increased in all subsites in individuals aged 50+ years. This was particularly evident for right sided cancer in the elderly of both sexes. There was a marked reduction in the incidence of left colonic cancer and rectal cancer in individuals under 50 years. In contrast, the incidence of right colonic cancer remained relatively stable in young individuals. Time trend studies indicate that the skewed subsite distribution of large bowel cancer in different age groups may increase with time and is probably due to varying etiological factors acting on different cohorts.The author thanks Mr. J. Fraser and the staff of the National Cancer Registry of New Zealand for their valuable assistance and Professor R. Beaglehole of the Department of Community Health, University of Auckland School of Medicine, for his helpful comments.     

Trends in the incidence of colorectal cancer at the Department of C?te-d'Or between 1976 and 1985

Colorectal cancer is the leading cause of cancer morbidity in France when both sexes are considered together. There are few available data on time trends, although such data would prove both necessary for planning screening programs and usefull to construct hypotheses on etiological factors. Data from the Registre des Tumeurs Digestives de C?te d'Or permitted to establish time trends for the different locations of colorectal cancer during the 1976-1985 period. Changes in incidence rates as based on the world reference population were studied using a log linear model as well as the Armitage test. Overall colon cancer rates have increased in both sexes. The mean annual increase of left colonic cancer was 3.1 p. 100 in men (p less than 0.05) and 4.0 p. 100 in women (NS), whereas rectal cancer decreased by 2.4 p. 100 in men and 3.3 p. 100 in women (NS). In men, left colonic cancer rates increased mainly in rural areas (+ 7.3 p. 100; p less than 0.05) whereas it increased mainly in urban areas in women (+ 6.0 p. 100; NS). In both sexes, the left colonic cancer increase was particularly noticeable in the 45-64 age group, which could indicate that the observed trend is likely to become more important in the next years. As for rectal cancer, the decrease was most important in the 65-74 age groups. That inversed trend for colon and rectum cancer has already been observed in other countries including the USA and Canada. As the trends we observed for right colon, left colon and rectal cancer differ, colorectal cancer etiology should be studied separately.     

性别与结直肠癌发病特点关系的分析

[目的]分析性别与结直肠癌临床特点的关系.[方法]收集2001-10-2011-10期间在华北地区6家医院检出结直肠癌患者资料,分析性别与发病年龄、肿瘤发生部位、腺癌分化程度的关系.[结果]2450例结直肠癌患者中男性1377例,女性1073例.男∶女为1.28∶1.00;女性发病率升高.右半结肠癌比例升高.性别与结直肠癌发生年龄、发生部位、腺癌分化程度均无明显的相关性(P＞0.05).[结论]结直肠癌发病率呈上升趋势,女性大肠癌患者比例有增加趋势.筛查是结直肠癌早诊早治的关键,筛查的起始年龄应按筛查目标确定.结直肠癌发病部位应重视右半结肠发病率升高现象,全结肠镜检查为首选.     

Overview of colorectal cancer in Japan

BACKGROUND AND PURPOSE: In Japan, the incidence of colorectal cancer has increased remarkably since World War II, and interest in this cancer has grown rapidly among Japanese clinicians and pathologists. As a result, the Japanese Society for Cancer of the Colon and Rectum started a multi-institutional registry of colorectal cancer in 1980. The purpose of this report is to present an overview of the actual state of surgical and pathologic aspects of colorectal cancer treated in the leading hospitals in Japan. MATERIALS AND METHODS: Registry files of clinical and pathologic findings for 38,369 patients treated between 1974 and 1986 with five-year follow-up information and 26,360 patients treated between 1991 and 1994 with no follow-up information were reviewed. RESULTS: Numbers of registered patients have increased annually, reflecting a trend toward an increasing incidence of this cancer in Japan. Colon cancer increased more than rectal cancer in both genders. Resection of the primary lesion was achieved in more than 97 percent of patients who underwent surgical operation recently. The curative resection rate has improved from 65.1 to 79.1 percent for colon cancer and from 71.4 to 80.4 percent for rectal cancer between the 1974 and 1979 and the 1991 and 1994 periods, and operative mortality of those has decreased from 1.8 and 2 percent to 0.5 and 0.5 percent, respectively. There was a trend toward a decrease in locally advanced cancer in terms of cancer invasion into the bowel wall. Stage IV colon cancer also decreased from 22.9 to 16.6 percent with time. The five-year survival rate of each pTNM stage has gradually been improving and was especially evident for patients with Stages I, II, and III of rectal cancer. Overall five-year survival rates for colorectal cancer patients currently exceeds 60 percent. CONCLUSION: The overall incidence of colorectal cancer and the ratio of colon cancer to rectal cancer patients in Japan are increasing. Results of surgical treatment are satisfactory with respect to curative resection rate, operative mortality, and the five-year survival rate. Registry data of the Japanese Society for Cancer of the Colon and Rectum are useful for reporting the actual state of diagnosis, treatment, and end results of colorectal cancer in Japan.     

广东地区3870例大肠癌的临床流行病学特征

目的探讨广东地区大肠癌的临床特点和发病规律。方法总结分析广州南方医院和惠州市中心人民医院1985—2004年经病理确诊的3870例大肠癌的资料。结果3870例大肠癌患者中位年龄55．3岁。好发年龄为41～70岁。其中青年大肠癌（年龄≤30岁）204例,占5．3％。随年龄增长,直肠癌逐渐减少,而右半结肠癌逐渐增加。男：女为1．42：1。3870例共检测出3958个病灶,其中单病灶3783例（97．8％）,多病灶87例（2．2％）。3958个病灶部位分别位于直肠2243例（56．7％）,左半结肠717例（18．1％）,右半结肠998例（25．2％）。组织学分型为：管状腺癌2943例（76．0％）,乳头状腺癌256例（6．6％）,黏液癌425例（11．0％）,其他246例（6．4％）。青年大肠癌分化不良者占38．2％,而中年和老年大肠癌只占29．9％和14．6％,差异有统计学意义（P〈0．01）。确诊时Dukes分期A、B、C和D期分别占234例（6．0％）,1936例（50．0％）,1310例（33．9％）和390例（10．1％）,其中进展期癌（B、C、D期）共3636例,占94．0％。结论近20年问广东地区大肠癌的收治率逐渐增加,并随年龄增长,直肠癌比例逐渐减少,而右半结肠癌比例逐渐增加。半数大肠癌发生于直肠,其次为右半结肠和左半结肠。广东地区大肠癌已失去中国大肠癌既往的三大临床流行病学特点。     

Changing site distribution of colorectal cancer in Japan

PURPOSE: In North America and other high-risk areas, there has been a proximal shift in the subsite distribution of colorectal cancer. We wanted to determine whether any similar change has occurred in Japan, and where the incidence of this disease has increased sharply. METHODS: Data from the Reports of the Japanese Society for Cancer of the Colon and Rectum were used to analyze the time trend of colorectal cancer in Japan between 1974 and 1994 according to the patients age at diagnosis and sex, and the site of the tumor within the colon or rectum. RESULTS: The percentage of patients over the age of 70, especially females, increased. The increase in the percentage of right-sided colon cancer in colorectal cancer cases was accompanied by a continuous decline in the percentage of rectal cancer in both sexes at all ages. In general, the percentage of right-sided colon cancer in colon cancer cases was stable in men, but increased in women. The rate among patients older than 70 years increased in men, but predominated and remained stable in women. No proximal shift in colon cancer was found in either sex under the age of 69. CONCLUSION: These findings indicated that a proximal shift in the subsite distribution of colorectal cancer has occurred in Japan. This rightward shift of colorectal cancer is due to the decreasing proportion of rectal cancer. Furthermore, the increasing proportion of older patients, especially females, may be another major determinant of the changing colon cancer subsite distribution.     

Change in anatomic distribution and incidence of colorectal carcinoma over a period of 15 years: clinical considerations

PURPOSE: Colorectal cancer is the second most common cancer in the Netherlands. Its incidence rates are among the highest in Europe. In the past decades, a right-sided shift of the subsite location of colorectal cancer has been reported. These changes in anatomic distribution might have clinical implications for the use of diagnostic or screening tools for colorectal cancer. This study was designed to investigate the change in incidence and anatomic distribution of colorectal cancer in a population over a period of 15 years. METHODS: The incidence of colorectal cancer in an eastern part of the Netherlands (700,000 inhabitants) was determined for two years, 1981 and 1996. From the regional laboratory of pathology, data including age, gender, subsite location, and Dukes classification were collected. The subsite location of colorectal cancer was divided into two groups: proximal and distal (the latter being within sigmoidoscopy reach). RESULTS: No differences in age and gender distribution were found. In 1981, the diagnosis of colorectal cancer was made in 232 patients in this region, and in 1996, it was made in 410 patients. The population remained almost stable during this time. Therefore, the incidence rose from 33 to 55 per 100,000 inhabitants from 1981 to 1996, respectively. In 1981, 25 percent of the carcinomas were proximal (to the sigmoid colon); this increased to 37 percent in 1996 ( P< 0.05). CONCLUSIONS: The incidence of colorectal cancer has almost doubled from 1981 to 1996 in this Dutch region. The proportion of proximal colorectal cancer has increased from 25 to 37 percent. These findings add to the notion that sigmoidoscopy is not the optimal diagnostic or screening tool for colorectal cancer.     

Environmental factors affect colon carcinoma and rectal carcinoma in men and women differently

BACKGROUND AND AIMS. Colon cancer is thought to be more closely associated with environmental factors than rectal cancer, but evidence is currently insufficient. We examined whether there are differences in the degree of environmental effect on colon cancer and rectal cancer in Japan. METHODS. We performed a birth cohort analysis for colon and rectal cancers using Japanese vital statistics from 1950 to 1998 and analyzed time trends by cancer site and gender. RESULTS. The mean annual increase in age-adjusted mortality rate from colon cancer was greater than that from rectal cancer and was greater in men than in women. In men left colon cancer showed the greatest rate of increase whereas cancer of the right colon showed only a slight change. Although left colon cancer rapidly increased until the middle 1980s and thereafter showed no change, right colon cancer showed no change until the middle 1980s and thereafter rapidly increased in men. However, the rates of increase in left colon cancer were greater than those in right colon cancer until the middle 1980s, after which a reversal in trend was seen in women. Birth cohort analysis indicates that for all cohorts the mortality rates at the same age were higher in the recent cohorts than in the previous ones. This trend was more marked for colon cancer than for rectal cancer and was stronger among men than among women. CONCLUSION. Colon cancer is more closely associated than rectal cancer with environmental factors, and this association is more pronounced in men than in women. Consequently cancers at these two sites should not be combined in studies of the role of lifestyle factors in causing these neoplasms. Furthermore, the causes of these diseases may differ in men and women.     

Age and sex distribution of patients with colorectal cancer

A retrospective review of 922 colorectal cancer patients was undertaken to determine whether the nonuniform anatomic distribution of colorectal cancer was influenced by age and/or sex. The mean age of patients with right colon lesions (71.2 years) was significantly higher than for either patients with left colon lesions (68.2 years) or rectal lesions (65.6 years). Further analysis disclosed that patients with proximal tumors were older than patients with distal tumors primarily because of the later presentation of females with cecal or ascending colon cancers. Comparison of the anatomic distribution of tumors in patient groups above and below the age of 70 revealed that right colon cancers accounted for a greater percentage of colorectal tumors in the older patient group than in the younger patient group. These findings support the roles played by both age and sex in influencing colorectal cancer location. Furthermore, these data provide a plausible explanation for the increasing incidence of proximal colonic lesions Presented at the Annual Residents' Night, New York Society of Colon and Rectal Surgeons, New York, New York, March 10, 1988.     

Is there a true "shift" to the right colon in the incidence of colorectal cancer?

OBJECTIVE: Previous studies have reported a migration in the occurrence of colorectal cancer (CRC) toward a proximal colonic location. To assess the potential impact of this, we evaluated recent temporal trends in the United States. METHODS: Using the nine population-based cancer registries that constitute the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute, we identified primary CRCs diagnosed between 1978 and 1998. Temporal changes were evaluated for 3-yr time periods. Age-adjusted incidence rates and the proportions of new diagnoses of CRC were calculated by site and by race. RESULTS: We identified 243,861 individuals with CRC during 1978-1998, 51.1% of whom were men. In whites and in blacks, the proportions of new diagnoses of right CRC rose significantly, from 34% and 37% to 40% and 44%, respectively. In contrast, the proportions of left CRC (in whites and blacks) and of rectosigmoid CRC (in whites) decreased significantly over time. For whites and blacks, the age-adjusted incidence rates for right CRC remained unchanged (in whites) or showed a small increase (in blacks), whereas the age-adjusted incidence rates for left CRC (in whites and blacks) and for rectosigmoid CRC (in whites) declined. During 1996-1998, right CRC was the most common site in the oldest age groups (70-79, 80 yr, and older) in whites and in blacks. CONCLUSIONS: The proximal migration of CRC over time is not attributed to a true increase in the incidence of right CRC. It is explained by a decrease in the incidence of distal CRC coupled with the aging of the population. Older individuals, in whom the burden of CRC is greatest, and in whom right CRC is the most common site, would be the most adversely affected from CRC screening methods that do not assess the total colon.     

Subsite distribution of colorectal carcinoma and implications for screening; a retrospective audit of 1771 cases

BACKGROUND/AIMS: Recent epidemiologic studies mentioned a shift from left to right in colorectal cancer. We searched our hospital database to try to give an insight into the patient characteristics and also optimize the screening programs in our country. METHODOLOGY: A total of 1771 colorectal cancer patients were identified and analyzed. Patients' gender, age, operation dates, tumor localization, resectability and T stage of the lesions, were recorded and comparisons were made. Second step of the study consisted of a questionnaire including 6 questions that were asked to 278 physicians to document current physician attitudes and practices regarding colorectal cancer screening, and to formulate appropriate interventions. RESULTS: Most of our patients were older than 51 in our study and a higher percentage of cases had sigmoid and rectal cancer (67%). The chronological trends in anatomic subsite distribution of colorectal cancer showed that by changing years when left colon cancer percentage was increasing, rectum cancer percentage was decreasing. There was no age-dependent variation in the topographical distribution of colorectal cancer by changing years. Also there was no relation between sex differences and subsite distribution when the whole group was taken into consideration. Specialist physicians had a poor understanding of colorectal cancer screening and lacked the responsibility of the screening programs. CONCLUSIONS: Data presented in this article do not support a progressive left to right shift in the distribution of colorectal carcinoma. Screening with fecal occult blood testing and sigmoidoscopy seems appropriate. Physician education may be an important step in screening before public awareness.     

I~III期结直肠癌淋巴结转移比率与预后关系

目的评价I~III期结直肠癌淋巴结转移比率与患者预后的关系。 方法回顾性分析中山大学附属第一医院胃肠胰腺外科2004年6月至2008年11月间446例行根治性切除的结直肠癌患者临床病理数据,探讨结直肠癌预后相关危险因素,评估结直肠癌淋巴结转移比率与患者预后的关系。 结果446例结直肠癌I、II、III期患者的5年总体生存率分别约为87.4%,83.1%和64.8%（Log-rank检验,P<0.001）。我们根据淋巴结转移比率（metastatic lymph node ratio, mLNR）将CRC患者分为三组：A组：mLNR为0;B组：mLNR为>0%~14%;C组：mLNR为>14%。A、B、C组三组患者的5年总体生存率分别约为84.3%、79.6%和49.1%（Log-rank检验,χ²=55.959,P<0.001）。就直肠癌患者而言,A、B、C三组5年生存率分别为79.0%、73.5%和43.2%（Log-rank检验,χ²=26.332,P<0.001）。而对于结肠癌患者来说三组的5年生存率分别为87.1%,80.8%和55.5%（Log-rank检验,χ²=21.214,P<0.001）。单因素和多因素Cox分析均显示,mLNR是结直肠癌独立的预后危险因素,随着mLNR的上升,结直肠癌患者的预后变差。 结论淋巴结转移比率（mLNR）是结直肠癌患者预后的独立危险因素,与N分期类似,但更有优势,可作为评估结直肠癌患者预后的指标之一。     

Right-side shift of metachronous colorectal adenomas after polypectomy

OBJECTIVE: In our previous study, we showed that the development of adenomas in the right-side colon increased with aging in subjects with no colorectal neoplasms. The aim of the present study was to investigate the location of metachronous colorectal adenomas after endoscopic polypectomy. MATERIAL AND METHODS: The records of a colonoscopic follow-up study on 2900 subjects after polypectomy were analyzed. The location was classified as the right-side colon and left-side colon at the splenic flexure. Subjects were classified into three groups according to distribution of adenomas at the initial two colonoscopies: those with adenomas located only in the left side (LL), adenomas in both the left side and right side (LR), and adenomas only in the right side (RR). Distribution of initial and metachronous adenomas was evaluated according to age. RESULTS: The annual incidence rates of colorectal adenomas in the left-side colon were estimated to be 8.56%, 11.2%, and 5.71% in the LL, LR, and RR groups, respectively. The rates in the right side were 5.91%, 15.5%, and 9.38%, respectively. The incidence rates in the left side in the age groups <40, 40-49, 50-59, and > or =60 years were 6.93%, 8.08%, 8.33%, and 8.48%/year, respectively. Those in the right side were 4.91%, 7.27%, 9.86%, and 12.41%/year, respectively. CONCLUSIONS: Although there may be individual predilection for right-side or left-side location of colorectal adenomas, aging tends to increase the number of adenomas in the right-side colon, while only modestly affecting those in the left-side colon.     

Trends in the age-related incidence of colon and rectal cancers in China, 2005–2015

BackgroundRecent evidences showed that the incidence of colorectal cancer decreased among older adults, yet this decline didn't appear in adults younger than 50 years. Our aim was to evaluate age-related incidence trends of colon and rectal cancers in China during 2005-2015.MethodsA retrospective study of colon and rectal cancers was conducted using population-based data from the Chinese Cancer Registry Annual Report. Age at diagnosis was analyzed in five sub-groups (0–19, 20–34, 35–49, 50–64 and 65 years). Data including new cases, incidence, and age-standardized rates (ASRs) were classified by sex and area. Temporal trends of ASRs were determined with Joinpoint regression analysis.ResultsFrom 2005 to 2015, colon cancer incidence decreased by -2.2% (95%CI: -3.1, -1.3) per year. A more steady decrease was seen in rectal cancer with AAPC of -0.9% (95%CI: -1.4, -0.4). Stratified by age at diagnosis, incidence trends followed a similar pattern, without age-related disparity. Females showed pronounced declines relative to males. The exception was that rural individuals showed opposite increasing trends, with 2.7% of AAPCs for colon cancer and 2.0% for rectal cancer.ConclusionA slight decline was observed in colon and rectal cancers during 2005–2015, regardless of age at diagnosis.     

Gender differences in the trend of colorectal cancer incidence in Singapore, 1968–2002

Background and aims Over the past decades, incidence trends of colorectal cancer are sharply increased in Singapore. In this population-based study we describe changes in colorectal cancer incidence in Singapore and explore the reasons behind these changes through age-period cohort (APC) modeling. Methods We included all 22,609 colorectal cancer cases reported to the Singapore Cancer Registry between 1968 and 2002. Poisson regression, using age-period (AP) and age-cohort (AC) models was used to determine the effects of age at diagnosis, calendar period, and birth cohort. Results Male colorectal cancer rates between 1968 and 2002 from 20 to 40 per 100,000 person years. The increase was sharpest among older men, for whom there was a significant AC effect. Female colorectal cancer rates increased until 1992 (from 16 to 29 per 100,000 person years) and stabilized afterward. For women under 65 years, we observed a significant AP effect, corresponding to a sudden rise in colorectal cancer incidence around 1978. Conclusions This study demonstrates important gender differences in colorectal cancer incidence in Singapore, with increasing rates among men, and stabilized rates in women. The increase in men is mainly attributable to an incidence increase in the oldest age groups, probably due to increased exposure to dietary and lifestyle risk factors earlier in life. The stabilization in female colorectal cancer risk could be due to lower exposure to lifestyle risk factors and prophylactic removal of precancerous lesions.     

Changing patterns of colorectal cancer in China over a period of 20 years

AIM: To determine whether any changes have occurred on the patterns of colorectal cancer in China.METHODS: Data from 21 Chinese articles published from 1980 to 1999, were used to analyze the time trend of colorectal cancer according to the patients' age at diagnosis,sex, the site of the tumor, stage, and the pathology.RESULTS: From 1980s to 1990s, the mean age of the colorectal cancer patients has increased. The percentage of the female patients rose. The distribution of colorectal carcinoma shows a predominance of rectal cancer. However,the proportion of proximal colon cancer (including transverse and ascending colon) increased significantly accompanied by a decline in the percentage of rectal cancer. Similarity in the percentage of distal colon cancer between two decades was revealed. In the 1990s, statistically more Stage B patients were found than those in 1980s. In addition, databases show a significant decrease in the Stage D cases. The proportion of adenocarcinoma increased, but the mucinous adenocarcinoma decreased during two decades.CONCLUSION: These findings indicate that the patternof colorectal cancer in China has been changing. Especially,a proximal shift due to the increasing proportion of ascending and transverse colon cancer has occurred in China.     

Nested case-control study on the risk factors of colorectal cancer

AIM: To investigate the risk factors of colon cancer and rectal cancer. METHODS: A nested case-control study was conducted in a cohort of 64 693 subjects who participated in a colorectal cancer screening program from 1989 to 1998 in Jiashan county, Zhejiang, China. 196 cases of colorectal cancer were detected from 1990 to 1998 as the case group and 980 non-colorectal cancer subjects, matched with factors of age, gender, resident location, were randomly selected from the 64 693 cohort as controls. By using univariate analysis and multivariate conditional logistic regression analysis, the odds ratio (OR) and its 95 % confidence interval (95 %CI) were calculated between colorectal cancer and personal habits, dietary factors, as well as intestinal related symptoms. RESULTS: The multivariate analysis results showed that after matched with age, sex and resident location, mucous blood stool history and mixed sources of drinking water were closely associated with colon cancer and rectal cancer, OR values for the mucous blood stool history were 3.508 (95 %CI: 1.370-8.985) and 2.139 (95 %CI: 1.040-4.402) respectively; for the mixed drinking water sources, 2.387 (95 %CI: 1.243-4.587) and 1.951 (95 %CI: 1.086-3.506) respectively. All reached the significant level with a P-value less than 0.05. CONCLUSION: The study suggested that mucous blood stool history and mixed sources of drinking water were the risk factors of colon cancer and rectal cancer. There was no any significant association between dietary habits and the incidence of colorectal cancer.     

Changing patterns of colorectal cancer in China over a period of 20 years

AIM: To determine whether any changes have occurred on the patterns of colorectal cancer in China. METHODS: Data from 21 Chinese articles published from 1980 to 1999, were used to analyze the time trend of colorectal cancer according to the patients' age at diagnosis, sex, the site of the tumor, stage, and the pathology. RESULTS: From 1980s to 1990s, the mean age of the colorectal cancer patients has increased. The percentage of the female patients rose. The distribution of colorectal carcinoma shows a predominance of rectal cancer. However, the proportion of proximal colon cancer (including transverse and ascending colon) increased significantly accompanied by a decline in the percentage of rectal cancer. Similarity in the percentage of distal colon cancer between two decades was revealed. In the 1990s, statistically more Stage B patients were found than those in 1980s. In addition, databases show a significant decrease in the Stage D cases. The proportion of adenocarcinoma increased, but the mucinous adenocarcinoma decreased during two decades. CONCLUSION: These findings indicate that the pattern of colorectal cancer in China has been changing. Especially, a proximal shift due to the increasing proportion of ascending and transverse colon cancer has occurred in China.     

Colorectal Cancer in Denmark 1943–1997

PURPOSE: This article reports the incidence rates of colon and rectal cancer in Denmark during 55 years of data registration and estimates the number of cases identified attributable to four modifiable risk factors and potentially preventable.METHODS: On the basis of reports in the nationwide, population-based, Danish Cancer Registry, we calculated age-standardized, period-specific, incidence rates and age and birth cohort-specific incidence rates. To calculate the population attributable risk, relative risk estimates were obtained from meta-analyses, case-control, and prospective cohort studies, combined with data from surveys of the consumption of alcohol, red meat, vegetables, and level of physical activity.RESULTS: For both genders, the incidence rate of colon cancer increased, whereas the incidence rate for rectal cancer decreased during the period 1943 to 1997. The decrease in the incidence rate of rectal cancer was observed for both genders, but the incidence rate among males was higher than that among females. The proportion of cases that could have been prevented if the Danish population had not been exposed to the four known risk factors varied from 0 to 15 percent for each of the four risk factors.CONCLUSIONS: This study shows that the incidence rate of colon cancer has increased, whereas that of rectal cancer has decreased in Denmark during 55 years of observation. The potentially preventable proportions of incident cases are substantial but not as high as might have been expected.Supported by the Danish Cancer Society and the National Institute of Public Health, Denmark.