Cancer: mixed messages, common purpose

Abstract

On Jan 2, a research paper published in Science by Cristian Tomasetti and Bert Vogelstein proclaimed that most individual cancers, 65%, could be attributed to “bad luck”—random events such as errors in DNA replication—rather than to environmental or inherited risk factors. This eyecatching message has drawn comment, partly because of the inbuilt uncertainty in the study's methods and headline estimate (with its 95% confidence interval of 39–81) and partly because of the conclusion's incompatibility with public health evidence and thinking. Owing to successes in medicine and public health, life expectancies have grown substantially over many years, especially in developed countries. According to the Global Burden of Disease Study 2013, global life expectancy for both sexes increased from 65·3 years to 71·5 years over the period 1990–2013. The good fortune of living longer brings with it an increased risk of cancer. World Cancer Day, which falls on Feb 4 and this year is themed Not beyond us, highlights the 8·2 million people expected to die of cancer, worldwide, every year. Yet almost half of these deaths are premature, in people aged 30–69 years. The overall burden of cancer morbidity and mortality remains substantially dependent on behavioural and environmental risk factors, including tobacco smoke, unhealthy diets and physical inactivity, and cancer-causing infectious diseases. In developing countries, the rapid and ongoing growth in non-communicable diseases can be expected to increase the burden of certain cancers, such as oesophageal cancer, in places where opportunities for treatment might be limited. Disparities in cancer outcomes between developing and developed countries are very pronounced: of the 236 000 women estimated to have died from cervical cancer in 2013, most lived in low-income countries. Cervical Health Awareness Month, marked in January, highlights an area of particular concern where screening and vaccination programmes should be able to protect all women and girls against papillomavirus infections and their consequences. In Cancer Statistics, 2015, published on Jan 5, the American Cancer Society's annual estimates of the cancer burden expected to be borne by the US population in the coming year anticipate some 1 658 000 new cancer cases in 2015, and 589 000 cancer deaths. Cancer death rates in the USA have fallen by 22% in 20 years, from 215·1 per 100 000 in 1991 to 168·7 per 100 000 in 2011. Here too, however, there are disparities in cancer survival, with cancer death rates in southern states having declined by just 15% over the relevant period, as compared with declines of 25–30% in states in the northeastern USA. In 2015, the leading cause of cancer death in the USA is anticipated to be the category of malignancies of the lungs and bronchi, at 28% of deaths in men and 26% of deaths in women. In a 5-year initiative recently announced by NHS England, referral of patients with suspected cancer is to be streamlined in an attempt to render earlier diagnoses and also to improve prognosis for patients with cancer. Often, cancer treatment itself is not only arduous for patients but also challenging for societies to organise and pay for. Also in the news in the UK has been the Cancer Drugs Fund, which provides substantial funding to benefit cancer patients in England, to pay for oncology drugs that are new or have not been adjudged cost effective by the National Institute for Health and Care Excellence. Cost pressures mean that the fund will grow to £340 million from April, 2015, but 25 drugs will not be available to new patients, including cabazitaxel for patients with advanced castration-resistant prostate cancer, and eribulin for patients with advanced breast cancer. The Cancer Drugs Fund owes its existence to the high cost of some cancer medicines and financial pressures on National Health Service provision, and its future beyond the end of its planned lifetime in March, 2016, is uncertain. Although 55 000 patients with cancer have benefited since the fund's inception in 2011, it is questionable whether a fund only for cancer medicines is equitable and cost effective for the NHS overall. Valuable though it is to understand molecular events involved in neoplasia, the importance and complexity of cancer call for clarity. Along with the imperative of providing effective cancer diagnosis and treatment in all settings, the public health agenda for cancer control must continue to be to promote healthy diet and exercise, and diminish tobacco smoking and other unhealthy behaviours, through individual and societal efforts.