In new Lancet paper, researchers call for large-scale study to know why
CANCER CASES in men outnumber those in women the world over but the situation is the reverse in India, according to a new paper published in the medical journal Lancet Oncology. And to understand why this is so, the paper says, India needs to conduct a largescale genomic study to identify country-specific biomarkers, which are compounds or gene fragments associated with a particular condition.
“The proportion of cancer diagnoses in India is higher in women than in men, which is in marked contrast to the worldwide age-standardised cancer incidence of a 25% higher incidence in men than in women. Cumulatively, breast, cervical, ovarian, and uterine cancer account for more than 70% of cancers in women in India,” says the paper co-authored by researchers from the National Institute of Cancer Prevention and Research-Indian Council of Medical Research (NICPR-ICMR).
The paper is based on a study which estimates that the burden of cancer in India is over 1.5 million new cases, for both sexes, and is predicted to nearly double in the next 20 years with age-adjusted mortality rates of 64.5 per 1,00,000 people.
What is more, it states, survival rates in India are poor. Fewer than 30% people survive five years or more after diagnosis.
India’s real cancer incidence for women is estimated to be 1-1.4 million per year. In 2015, reported incidence of cancer in India was 0.7 million, the third highest after China and the US.
According to NICPR data, around 2,00,100 men and 1,95,300 women die of cancer every year. But with the sex ratio at 943 females per 1,000 males, according to the 2011 Census, the rate of cancer deaths in Indian women is higher than that in Indian men.
The paper argues that understanding differences that are specific to India through genomics could enable the identification of women who are at a high risk of developing cancer, making targeted screening cost-effective.
The India-specific genetic biomarkers that urgently need to be identified, it says, are those related to the intermediates of breast cancer, such as mammographic density.
Basic screening coverage is the need of the hour, says Dr Ravi Mehrotra, director NICPR-ICMR and one of the authors of the paper alongside those from the University of Birmingham and the Southeast Asia regional office of WHO.
“More than 90% of all female cancers are not inherited, so genomic screening is not a cost effective option. But if we can do a basic screening of 80% of the population, that would go a long way. There was an earlier plan but now work has started for training manpower for screening for cervical, breast and oral cancers,” he says.
“The problem is that there are questions about how effective mammograms are for breast cancer screening. In our country, additionally, we don’t have enough machines or trained radiologists to read mammograms. So, it is either a clinical examination or a breast self-examination. For cervical cancer, pap smear is too costly. There is the visual inspection with acetic acid for which people are being trained,” says Dr Mehrotra.
In 2010, India launched the National Program for Prevention and Control of Cancer, Diabetes, Cardio Vascular Diseases and Stroke (NPCDCS), under which screening was supposed to have been undertaken for cervical, breast and oral cancers. But the programme did not take off.
The plan to screen for cancers and CVDs was revived in 2016 with an initial aim of rolling it out in 100 districts — the number has now gone up to 165.
Published last month, the Lancer Oncology study contains three key recommendations:
* “Large-scale studies recruiting unselected women with breast, ovarian, and uterine cancer from across rural and urban regions of India are urgently needed.”
* “Studies should incorporate clinical, pathological, and survival data from Indian women tested with pan-cancer panels using next-generation sequencing to characterise the prevalence and spectrum of mutations and variants of uncertain significance.”
* “To tease apart intrinsic biological differences from environmental factors, and to assess the interplay of these two factors, data should be collected on epidemiological characteristics and environmental exposures to potential carcinogens.”