Closing in on cancer

Science will win the technical battle against cancer. But that is only half the fight

THE numbers are stark. Cancer claimed the lives of 8.8m people in 2015; only heart disease caused more deaths. Around 40% of Americans will be told they have cancer during their lifetimes. It is now a bigger killer of Africans than malaria. But the statistics do not begin to capture the fear inspired by cancer’s silent and implacable cellular mutiny. Only Alzheimer’s exerts a similar grip on the imagination.

Confronted with this sort of enemy, people understandably focus on the potential for scientific breakthroughs that will deliver a cure. Their hope is not misplaced. Cancer has become more and more survivable over recent decades owing to a host of advances, from genetic sequencing to targeted therapies. The five-year survival rate for leukemia in America has almost doubled, from 34% in the mid-1970s to 63% in 2006-12. America is home to about 15.5m cancer survivors, a number that will grow to 20m in the next ten years. Developing countries have made big gains, too: in parts of Central and South America, survival rates for prostate and breast cancer have jumped by as much as a fifth in only a decade.

From a purely technical perspective, it is reasonable to expect that science will one day turn most cancers into either chronic diseases or curable ones. But cancer is not fought only in the lab. It is also fought in doctors’ surgeries, in schools, in public-health systems and in government departments. The dispatches from these battlefields are much less encouraging.

Cell-side research

First, the good news. Caught early, many cancers are now highly treatable. Three out of four British men who received a prostate-cancer diagnosis in the early 1970s did not live for another ten years; today four out of five do. Other cancers, such as those of the lung, pancreas and brain, are harder to find and treat. But as our Technology Quarterly in this issue shows, progress is being made. Techniques to enable early diagnosis include a device designed to detect cancer on the breath; blood tests can track fragments of DNA shed from tumours. Genome sequencing makes it ever easier to identify new drug targets.

The established trio of 20th-century cancer treatments—surgery, radiation and chemotherapy—are all still improving. Radiotherapists can create webs of gamma rays, whose intersections deliver doses high enough to kill tumours but which do less damage to healthy tissue as they enter and leave the body. Some new drugs throttle the growth of blood vessels bringing nutrients to tumours; others attack cancer cells’ own DNA-repair kits. Cancer may be relentless; so too is science.

The greatest excitement is reserved for immunotherapy, a new approach that has emerged in the past few years. The human immune system is equipped with a set of brakes that cancer cells are able to activate; the first immunotherapy treatment in effect disables the brakes, enabling white blood cells to attack the tumours. It is early days, but in a small subset of patients this mechanism has produced long-term remissions that are tantamount to cures. Well over 1,000 clinical trials of such treatments are under way, targeting a wide range of different cancers. It is even now possible to reprogram immune cells to fight cancer better by editing their genomes; the first such gene therapy was approved for use in America last month.

Yet cancer sufferers need not wait for the therapies of tomorrow to have a better chance of survival today. Across rich and poor countries, the survivability of cancer varies enormously. Men die at far higher rates than women in some countries; in other countries, at similar levels of development, they do comparably well. The five-year survival rate for a set of three common cancers in America and Canada is above 70%; Germany achieves 64%, whereas Britain manages a mere 52%. Disparities exist within countries, too. America does well in its treatment of cancer overall, but suffers extraordinary inequalities in outcomes. The death rate of black American men from all cancers is 24% higher than it is for white males; breast-cancer death rates among blacks are 42% higher than for whites. A diagnosis in rural America is deadlier than one in its cities.

Practical as well as pioneering

Variations between countries are partly a reflection of health-care spending: more than half of patients requiring radiotherapy in low- and middle-income countries do not have access to treatment. But big budgets do not guarantee good outcomes. Iceland and Portugal do not outspend England and Denmark on health care as a proportion of GDP, but past studies show wide variation in survivability in all cancers.

Instead, the problem is often how money is spent, not how much of it there is. To take one example, a vaccine exists against the human papillomavirus (HPV), which causes cancers of the cervix in women, as well as cancers of the head and neck. Rwanda started a programme of routine vaccination in 2011, and aims to eradicate cervical cancer by 2020. Other countries are far less systematic. Vaccinations could help prevent cervical cancer in 120,000 Indian women each year.

Policymakers are not powerless. More can be done to verify which treatments (and combinations thereof) work best. A £1.3bn ($2bn) cancer-drug fund in England, which made expensive new medicines easier to obtain, did not assess the efficacy of the drugs it provided—a huge missed opportunity. Measuring the incidence and survival of cancer, through cancer registries, spotlights where patients are being failed. Access to health care matters, too: the number of Americans whose cancers were diagnosed at the earliest possible opportunity went up after Obamacare was enacted. And prevention remains the best cure of all. Efforts to rein in tobacco use averted 22m deaths (many of them to cancer) between 2008 and 2014. Yet only a tenth of the world’s population lives in countries where taxes make up at least three-quarters of the price of cigarettes, as recommended by the World Health Organisation.

Taxes and budgeting are a lot less exciting than tumour-zapping proton beams and antibodies with superpowers. But the decisions of technocrats are as important as the work of technicians. Cancer kills millions of people not simply for want of scientific advance, but also because of bad policy.

Fonte: The Economist

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