Cancers in Australia in 2010 attributable to and prevented by the use of combined oral contraceptives

Objectives: To estimate the proportion and number of cancers occurring in Australia in 2010 attributable to combined oral contraceptive pill (OCP) use. Methods: We estimated the population attributable fraction (PAF) for cancers causally associated with combined OCP use (breast, cervix), and the proportion of endometrial and ovarian cancers prevented (prevented fraction [PF]). We used standard formulae incorporating prevalence of combined OCP use in the Australian population, relative risks of cancer associated with this exposure and cancer incidence. Results: An estimated 105 breast and 52 cervical cancers (0.7% and 6.4% of each cancer, respectively) in Australia in 2010 were attributable to current use of combined OCP. Past combined OCP use was estimated to have prevented 1,032 endometrial and 308 ovarian cancers in 2010, reducing the number of cancers that would otherwise have occurred by 31% and 19%, respectively. Conclusions: A small proportion of breast and cervical cancers is attributable to combined OCP use; OCP use is likely to have prevented larger numbers of endometrial and ovarian cancers. Implications: Women seeking contraceptive advice should be told of potential adverse effects, but should also be told that – along with reproductive health benefits – combined OCP use can reduce long‐term risks of ovarian and endometrial cancers.     

Cancers in Australia in 2010 attributable to modifiable factors: introduction and overview

Objective: To describe the approach underpinning a national project to estimate the numbers and proportions of cancers occurring in Australia in 2010 that are attributable to modifiable causal factors. Methods: We estimated the population attributable fraction (PAF) (or prevented fraction) of cancers associated with exposure to causal (or preventive) factors using standard formulae. Where possible, we also estimated the potential impact on cancer incidence resulting from changes in prevalence of exposure. Analyses were restricted to factors declared causal by international agencies: tobacco smoke; alcohol; solar radiation; infectious agents; obesity; insufficient physical activity; insufficient intakes of fruits, vegetables and fibre; red and processed meat; menopausal hormone therapy (MHT); oral contraceptive pill (OCP); and insufficient breast feeding. Separately, we estimated numbers of cancers prevented by: aspirin; sunscreen; MHT; and OCP use. We discuss assumptions pertaining to latent periods between exposure and cancer onset, choices of prevalence data and risk estimates, and approaches to sensitivity analyses. Results: Numbers and population attributable fractions of cancer are presented in accompanying papers. Conclusions: This is the first systematic assessment of population attributable fractions of cancer in Australia.     

Cancers in Australia in 2010 attributable to modifiable factors: summary and conclusions

Objective: To estimate the numbers and proportions of cancers occurring in Australia in 2010 attributable to modifiable causal factors. Methods: We estimated the population attributable fraction (PAF) of cancers associated with exposure to 13 causal factors using standard formulae incorporating exposure prevalence and relative risk data. We also calculated the potential impact of changing exposure to some factors. Results: A total of 32% of all cancers diagnosed in Australia in 2010 (excluding keratinocyte cancers) were attributable to the 13 factors assessed (men 33%; women 31%). Leading factors were tobacco smoke (PAF all cancers: 13.4%), solar radiation (6.2%), inadequate diet (6.1%) and overweight/obesity (3.4%). Factors conferring highest PAFs differed by sex: highest PAFs for men were tobacco smoke (15.8%), solar radiation (7.1%) and alcohol (3.0%); while highest PAFs for women were tobacco smoke (10.1%), solar radiation (5.0%) and overweight/obesity (4.5%). Sites with the highest counts of potentially preventable cancers were lung (8,569), colorectal (7,404), melanoma of the skin (7,220) and breast (3,233). Conclusions: At least one in three cancers in Australia is attributable to exposure to known modifiable factors. Implications: Up to 37,000 cancers could be prevented in Australia each year if the population avoided exposure to 13 common factors known or strongly suspected to cause cancer.     

Cancers in Australia in 2010 attributable to the consumption of alcohol

Objective: To estimate the proportion and numbers of cancers occurring in Australia in 2010 that are attributable to alcohol consumption. Methods: We estimated the population attributable fraction (PAF) of cancers causally associated with alcohol consumption using standard formulae incorporating prevalence of alcohol consumption and relative risks associated with consumption and cancer. We also estimated the proportion change in cancer incidence (potential impact fraction [PIF]) that might have occurred under the hypothetical scenario that an intervention reduced alcohol consumption, so that no‐one drank >2 drinks/day. Results: An estimated 3,208 cancers (2.8% of all cancers) occurring in Australian adults in 2010 could be attributed to alcohol consumption. The greatest numbers were for cancers of the colon (868) and female breast cancer (830). The highest PAFs were for squamous cell carcinomas of the oral cavity/pharynx (31%) and oesophagus (25%). The incidence of alcohol‐associated cancer types could have been reduced by 1,442 cases (4.3%) – from 33,537 to 32,083 – if no Australian adult consumed >2 drinks/day. Conclusions: More than 3,000 cancers were attributable to alcohol consumption and thus were potentially preventable. Implications: Strategies that limit alcohol consumption to guideline levels could prevent a large number of cancers in Australian adults.     

Cancers in Australia in 2010 attributable to tobacco smoke

Objectives: To estimate the population attributable fraction (PAF) and numbers of cancers occurring in Australia in 2010 attributable to tobacco smoking, both personal and by a partner. Methods: We used a modified Peto‐Lopez approach to calculate the difference between the number of lung cancer cases observed and the number expected assuming the entire population developed lung cancer at the same rate as never smokers. For cancers other than lung, we applied the standard PAF formula using relative risks from a large cohort and derived notional smoking prevalence. To estimate the PAF for partners' smoking, we used the standard formula incorporating the proportion of non‐smoking Australians living with an ever‐smoking partner and relative risks associated with partner smoking. Results: An estimated 15,525 (13%) cancers in Australia in 2010 were attributable to tobacco smoke, including 8,324 (81%) lung, 1,973 (59%) oral cavity and pharynx, 855 (60%) oesophagus and 951 (6%) colorectal cancers. Of these, 136 lung cancers in non‐smokers were attributable to partner tobacco smoke. Conclusions: More than one in eight cancers in Australia is attributable to tobacco smoking and would be avoided if nobody smoked. Implications: Strategies to reduce the prevalence of smoking remain a high priority for cancer control.     

Protection from sunlight, particularly for children

Excessive exposure to ultraviolet radiation (UVR) in childhood has been recognized as an extrinsic risk factor for the development of skin cancer later in life. The risk of squamous cell carcinoma is clearly related to the lifetime accumulated UVR dose, while the risk of melanoma and basal cell carcinoma is increased by intermittent UVR exposure, which is frequently responsible for sunburn. Besides UVR exposure, several intrinsic factors increase the risk of skin cancer, especially the risk of melanoma, such as skin type, the number of normal and dysplastic melanocytic naevi and family history. Responsible sun behaviour in childhood is most important to prevent skin cancer: stay in the shade, especially between 12:00 and 3:00 p.m., wear protective clothing, including a hat and sunglasses, try to build-up natural adaptation of the skin to UVR and apply a sunscreen to UVR exposed skin. There are strong indications that the possible preventive effect of sunscreens on the development of skin cancer is abolished in case of prolonged and intensive UVR exposure, because of a false feeling of safety. The most important measure to prevent the development of melanomas and basal cell carcinomas is probably the prevention of sunburn in childhood.     

Cancers in Australia in 2010 attributable to total breastfeeding durations of 12 months or less by parous women

Objectives: To estimate the proportion and number of cancers occurring in Australia in 2010 attributable to parous women having breastfed for total durations of ≤12 months. Methods: We estimated the population attributable fraction (PAF) of breast cancers (the only cancer site with convincing evidence of causal association) associated with women breastfeeding for ≤12 months in total, using standard formulae incorporating breastfeeding prevalence data, relative risks associated with breastfeeding and cancer incidence. We also estimated the proportion change in disease incidence (potential impact fraction [PIF]) that might have occurred under two hypothetical scenarios of women breastfeeding for longer durations. Results: An estimated 235 (1.7%) breast cancer cases that occurred in Australian in 2010 could be attributed to women breastfeeding for total durations of ≤12 months. Assuming a hypothetical increase in breastfeeding, we estimated that the number of breast cancers prevented would range from 36 to 51 (prevented fraction = 0.3% to 0.4%). Conclusions: More than 200 breast cancers were attributable to women breastfeeding for total durations of ≤12 months. Implications: Policies to increase breastfeeding duration may help prevent breast cancers in the future.     

Cancers in Australia in 2010 attributable to and prevented by the use of menopausal hormone therapy

Objectives: To estimate the proportion and number of cancers occurring in Australia in 2010 attributable to menopausal hormone therapy (MHT) use. Methods: We estimated the population attributable fraction for cancers causally associated with MHT (breast, endometrium, ovary), and the proportion of colorectal cancers prevented by MHT. We used standard formulae incorporating Australian prevalence data, relative risks of cancer associated with MHT and cancer incidence. We also estimated potential change in cancer incidence under two hypothetical scenarios whereby 25% fewer Australian women used MHT, or women exclusively used oestrogen‐only MHT. Results: An estimated 539 cancers in Australia in 2010 were attributable to MHT: 453 breast, 67 endometrial and 19 ovarian cancers equating to 3.4%, 3.1% and 1.6% of each cancer type, respectively. In contrast, MHT may have prevented 52 colorectal cancers. If 25% fewer women used MHT, then 141 cancers may have been avoided. If women exclusively used oestrogen‐only MHT then 240 cancers may have been avoided. Conclusions: MHT use caused more than 500 cancers in Australian women in 2010 and prevented ～50 colorectal cancers. Implications: MHT use continues to cause an excess of cancers. The risks, benefits, regimen and treatment duration should be carefully considered for each woman before MHT is commenced.     

When to apply sunscreen: a consensus statement for Australia and New Zealand

Introduction : Cancers of the skin are the most common cancers in humans, with Australia and New Zealand having the world’s highest incidence. Primary prevention campaigns advise people to apply sunscreen to exposed body sites when outdoors. However, despite growing evidence that cumulative sub‐erythemal exposures cause mutational damage, and trial data demonstrating benefit from daily sunscreen use, current policies do not consider the hazards of incidental (everyday) sun exposure. Thus, a Sunscreen Summit was convened to review the evidence and update the policies for people living in Australia and New Zealand. Results : After reviewing the benefits and risks of sunscreen application, the policy group concluded that people living in Australia and New Zealand should be advised to apply sunscreen to the face/head/neck and all parts of the body not covered by clothing on all days when the ultraviolet index is forecast to reach three or greater, irrespective of their anticipated activities. For planned outdoors activities, sunscreen should be used alongside other sun protection measures. Conclusions : People living in Australia and New Zealand are now advised to apply sunscreen every day when the UV index is predicted to reach 3 or above. Implications for public health : Increased use of sunscreen as part of the daily routine to reduce incidental sun exposure will lead to decreased incidence of skin cancer in the future.     

Cancers in Australia in 2010 attributable to insufficient physical activity

Objectives: To estimate the proportion and numbers of cancers occurring in Australia in 2010 attributable to insufficient levels of physical activity. Methods: We estimated the population attributable fraction (PAF) of cancers causally associated with insufficient physical activity (colon, post‐menopausal breast and endometrium) using standard formulae incorporating prevalence of insufficient physical activity (<60 minutes at least 5 days/week), relative risks associated with physical activity and cancer incidence. We also estimated the proportion change in cancer incidence (potential impact fraction [PIF]) that may have occurred assuming that everyone with insufficient activity levels increased their exercise by 30 minutes/week. Results: An estimated 1,814 cases of colon, post‐menopausal breast and endometrial cancer were attributable to insufficient levels of physical activity: 707 (6.5%) colon; 971 (7.8%) post‐menopausal breast; and 136 (6.0%) endometrial cancers. If those exercising below the recommended level had increased their activity level by 30 minutes/week, we estimate 314 fewer cancers (17% of those attributable to insufficient physical activity) would have occurred in 2010. Conclusions: More than 1,500 cancers were attributable to insufficient levels of physical activity in the Australian population. Implications: Increasing the proportion of Australians who exercise could reduce the incidence of several common cancers.     

Cancers in Australia in 2010 attributable to infectious agents

Objectives: To estimate the proportion and numbers of cancers in Australia in 2010 attributable to infectious agents. Methods: The population attributable fraction (PAF) and number of cancers caused by hepatitis B and C viruses (HBV, HCV), Helicobacter pylori and human immunodeficiency virus (HIV) were calculated using standard formulae incorporating prevalence of infection in the Australian population, the relative risks associated with that infection and cancer incidence. For cancers with very strong associations to the infectious agent (Epstein‐Barr virus [EBV], human papillomavirus [HPV] and HIV/Kaposi's sarcoma herpes virus [KSHV]), calculations were based on viral prevalence in the tumour. Results: An estimated 3,421 cancers (2.9% of all cancers) in Australia in 2010 were attributable to infections. Infectious agents causing the largest numbers of cancers were HPV (n=1,706), H. pylori (n=793) and HBV/HCV (n=518). Cancer sites with the greatest number of cancers caused by infections were cervix (n=818), stomach (n=694) and liver (n=483). Cancers with highest proportions attributable to infectious agents were Kaposi's sarcoma (100%), cervix (100%), nasopharynx (87%), anus (84%) and vagina (70%). Conclusions: Infectious agents cause more than 3,000 cancers annually in Australia. Implications: Opportunities for cancer prevention through infection control are considerable, even in a ‘first world’ nation like Australia.     

Cancers prevented in Australia in 2010 through the consumption of aspirin

Objectives: To estimate the proportion and number of cancers in Australia in 2010 that may have been prevented from occurring due to daily use of aspirin in the population. Methods: We calculated the Prevented Fraction (PF) of colorectal and oesophageal cancers using standard formulae. The PF is the proportion of the hypothetical total load of cancer in the population that was prevented by exposure to aspirin. The formula incorporates estimates of the prevalence of aspirin use in Australian adult populations, the relative risks associated with aspirin use and cancer incidence. Results: An estimated 335 colorectal cancers, 22 oesophageal adenocarcinomas and 29 oesophageal squamous cell carcinomas (SCC) were potentially prevented due to daily aspirin use. These figures equate to 2.2%, 3.1% and 5.4% of all colorectal cancers, oesophageal adenocarcinomas and oesophageal SCCs, respectively, that would otherwise have occurred but were potentially avoided due to the daily use of aspirin pertaining in the Australian population. Conclusions: At current levels of consumption, a small but measurable reduction in cancer incidence can be attributed to daily aspirin use. Implications: Assuming the benefits outweigh the harms of known gastrointestinal toxicity and other hazards, aspirin use may be considered for some people to prevent the development of particular gastrointestinal cancers.     

Cancers in Australia in 2010 attributable to the consumption of red and processed meat

Objectives: To estimate the proportion and numbers of cancers in Australia in 2010 attributable to consuming red/processed meat. Methods: We estimated the population attributable fraction (PAF) for cancers causally associated with red/processed meat consumption (colon, rectum) using standard formulae incorporating prevalence of consumption (1995 National Nutrition Survey), relative risks associated with consumption and cancer incidence. We also estimated the proportion change in cancer incidence (potential impact fraction [PIF]) that might have occurred under two hypothetical interventions whereby Australian adults reduced their consumption of red/processed meat from prevailing levels to ≤100 g or ≤65 g per day, respectively. Results: An estimated 2,614 cases (18%) of colorectal cancer occurring in Australians in 2010 were attributable to red/processed meat consumption (16% of colon cancers; 23% of rectal cancers). We estimated that if all Australian adults had consumed ≤65 g/day or ≤100 g/day of red/processed meat, then the incidence of colorectal cancer would have been 5.4% (798 cancers) or 1.4% (204 cancers) lower, respectively. Conclusions: About one in six colorectal cancers in Australians in 2010 were attributable to red/processed meat consumption. Implications: Reducing red/processed meat intake may reduce colorectal cancer incidence, but must be balanced against nutritional benefits of modest lean meat consumption.     

Cancers in Australia in 2010 attributable to inadequate consumption of fruit,non‐starchy vegetables and dietary fibre

Objectives: To estimate the number and proportion of cancers occurring in Australia in 2010 attributable to consumption deficits in fruit, non‐starchy vegetables and dietary fibre. Methods: We estimated the population attributable fraction (PAF) for cancers causally associated with inadequate intake of fruit and non‐starchy vegetables (oral cavity, pharynx, oesophageal squamous cell carcinoma, stomach, larynx); inadequate intake of fruit (lung); and insufficient intake of fibre (colorectum). We used standard formulae incorporating prevalence of exposure (1995 National Nutrition Survey) and relative risks from independent studies. Results: Overall, 1,555 (1.4% of all) and 311 (0.3% of all) cancers were attributable to inadequate intakes of fruit and non‐starchy vegetables, respectively. A further 2,609 colorectal cancers (18% of colorectal) were attributable to insufficient fibre intake. If Australians increased their fibre intake by eating the recommended daily intakes of fruit and vegetables, an estimated 1,293 (8.8%) colorectal cancers could be prevented. Conclusions: One in six colorectal cancer cases was attributable to inadequate intake of dietary fibre and about 1,800 cancers at other sites were attributable to insufficient fruit and non‐starchy vegetable consumption. Implications: Increasing the proportion of Australians who consume the recommended intake of fruit, vegetables and fibre could prevent up to 4% of all cancers.     

Multiplicity of skin cancers in Queensland and their cost burden to government and patients

Objective: To determine the cost burden to government and patients for individuals with multiple skin cancers. Methods: We used self‐reported baseline data on socio‐demographics, phenotype and sun exposure behaviours from participants in the QSkin Sun and Health Study with at least one histopathologically confirmed keratinocyte cancer or melanoma (n=5,673). Linkage to Australian Medicare data (2011–2014) provided resource data and government and out‐of‐pocket patient costs. Generalised linear models examined costs by frequency of skin cancer groups separately for melanoma and keratinocyte cancer. Results: Over three years, 539 participants were diagnosed with melanoma (11% had ≥2 melanomas) and 5,134 participants were treated for keratinocyte cancers (10% had ≥6). Median Medicare costs per person were $1,325 (maximum $6,117) for ≥2 melanomas and $2,126 (maximum $54,618) for ≥6 keratinocyte cancers. Increased costs were associated with private health insurance. Conclusions: Individuals who are multiply affected by skin cancers are relatively common and the accompanying individual and government cost burden can be substantial. These findings support skin cancer being classified as a chronic disease. Implications for public health: Over time, the economic burden for skin cancer for individuals and health providers is high and investment in prevention remains important from an economic viewpoint.     

Cancers in Australia in 2010 attributable to overweight and obesity

Objectives: To estimate the proportion and number of cancers occurring in Australia in 2010 attributable to overweight/obesity. Methods: We estimated the population attributable fraction (PAF) and number of cancers causally associated with overweight/obesity. We used standard formulae incorporating Australian prevalence data for body mass index (BMI), relative risks associated with BMI and cancer. We also estimated the proportion change in cancer incidence (potential impact fraction [PIF]) that may have occurred assuming that the prevalence of overweight/obesity had remained at 1990 levels. Results: An estimated 3,917 cancer cases (3.4% of all cancers) diagnosed in 2010 were attributable to overweight/obesity, including 1,101 colon cancers, 971 female post‐menopausal breast cancers and 595 endometrial cancers (PAFs of 10%, 8% and 26%, respectively). Highest PAFs were observed for oesophageal adenocarcinoma (31%), endometrial cancer (26%) and kidney cancer (19%). If the prevalence of overweight/obesity in Australia had remained at levels prevailing in 1990, we estimate there would have been 820 fewer cancers diagnosed in 2010 (PIF 2%). Conclusions: Overweight/obesity causes a substantial number of cancers in Australia. Implications: Public health strategies to reduce the prevalence of overweight and obesity will reduce the incidence of cancer, particularly of the colon, breast and endometrium.     

Skin Cancer Prevention: A Time for Action

Skin cancer is the most common malignancy in the United States accounting for more than 840,000 cases and 9,400 deaths annually. It is estimated that 90% of non-melanoma skin cancers and much of melanoma incidence can be attributed to sun exposure. The evidence suggests that regular use of sunscreen (Sun Protective Factor (SPF) of 15 or higher), wearing protective, tightly woven clothing and wide brimmed hats, and avoiding sun exposure when the ultraviolet rays are strongest (between 11:00 a.m. and 3:00 p.m.) can dramatically reduce the risk of skin cancer. Interventions to promote sun-protection behaviors that target children and adults are necessary to reduce the growing incidence rate of skin cancer in the United States.MA during the time of this research     

Long-term increase in sunscreen use in an Australian community after a skin cancer prevention trial

BACKGROUND: Given the public health burden of skin cancer in white populations, an increase in sun protective behavior is needed. In a high-risk community, we assessed long-term sunscreen use among people who had participated in a randomized trial of daily sunscreen application for prevention of skin cancer. METHODS: In 1992, 1621 residents of the subtropical Australian township of Nambour were randomly allocated to either daily or discretionary sunscreen use until 1996. From 1997 to 2002, we monitored by questionnaires their ongoing sunscreen use. RESULTS: People who had never or irregularly used sunscreen when in summer sun before the trial were more likely (P < 0.0001) to be sustaining regular application especially to their face (20% vs. 11%) and forearms (14% vs. 5%) if they had been allocated to daily, not discretionary, use of sunscreen for 5 years. CONCLUSIONS: Regular voluntary sunscreen use for skin cancer prevention can be sustained by sun-sensitive people in the long term. Habit formation appears to be an important goal for sun protection programs among those living, or on vacation, in sunny places.     

Estimate of the proportion of skin tumors attributable to sun exposure in 3 Italian populations

Translation of recommendations on skin cancer prevention formulated by many national and international institutions into efficient steps requires measuring the potential impact in terms of preventable cases. This study analyses the proportion of skin cancers attributable to sun exposure in Turin, Trento and Ragusa. Estimates have been reached by applying the risk models calculated from the case-control study on melanoma in Turin and the Helios multi-centric study on skin carcinomas. The proportion of cases attributable to sun exposure has been subsequently calculated by correcting for the different proportion of skin characteristics among the populations taken into consideration. Attributable risks so calculated show medium to high values for melanoma in Turin (38%) and Trento (29%), while values are lower in Ragusa (17%). As for basal-cell carcinoma, attributable risk values are slightly inferior to those of melanoma. The risk of squamous-cell carcinoma attributable to sun exposure during outdoor work is the highest in Ragusa, with a value of 25%. Taking an annual incidence rate for melanoma of 9 cases per 100,000 inhabitants, and a preventive intervention with 50% of effectiveness, preventable cases should be 2 cases per 100,000 each year. This figure compared with 8 preventable cases of cervix cancer, in a similar population suggests an extremely cautious attitude in taking on programmes aiming to change life styles.