The story of the Mumbai breast screening study

It was the early 1990s; with the collapse of the Soviet Union, an ambitious WHO sponsored randomised trial of breast self-examination was in disarray. Data from the Moscow component of the trial were never published, and early reports emerging from the Leningrad part of the study suggested that breast self-examination was unlikely to show a reduction in mortality from breast cancer.

At the same time, the incidence of breast cancer in India and other low and middle income countries (LMICs) was rapidly rising. With most patients presenting in advanced stages, a screening strategy was needed that would mitigate the rise in mortality from the disease. Mammography was, by then, well established as an effective screening modality in the Western world; however, it was clearly not the answer for LMICs due to inadequate infrastructure and logistical challenges.

Clinical breast examination was the obvious choice at that time. But there was little information available on its effectiveness, so this could not be applied for population screening. Encouraging results were, however, emerging from the Canadian National Breast Screening Study (CNBSS). Early results of the study published in 1992 revealed that, in women aged 50-59 years, mammography provided little added benefit over clinical breast examination in terms of mortality reduction. These results made it imperative that a randomised trial of clinical breast examination versus no screening was conducted.

At the Tata Memorial Centre (TMC), we were keen to take up this challenge and answer this important public health question, but funding was the elusive element. After much effort and with seed money provided by an unrestricted grant, we undertook a pilot study to detect breast cancer by clinical breast examination with the help of trained female health workers who examined women in their homes. We conducted the study in the lower middle income areas around our institute. After examining 4000 participants, we detected two women with breast cancer.

We presented these results at the 1994 UICC Cancer Congress in New Delhi. At the end of our presentation, an American gentleman walked up to us and suggested that we apply for a grant for a larger study from the US National Cancer Institute (NCI). It was only when he handed us his business card that we realised he was the head of the funding department of NCI. The relevant application forms were received, and we prepared an ambitious protocol for a randomised trial of clinical breast examination versus no screening. Our application was successful: the NCI agreed to fund our trial, provisionally for 15 years through a R01 grant.

Our original plan was to recruit 70 000 women aged 35-64 years. But this had to be revised twice as we gained experience and learnt the ground realities of population screening in deprived sections of society. In the end, our sample size shot up to 150 000. The districts or clusters that we had chosen were in congested slums in Mumbai and this posed many hurdles. Some of the challenges that we faced included visiting each household in narrow and congested alleys, recording their precise postal addresses which were often ambiguous, and counselling women about participation in the study in an easy to understand way. We also had to involve local community leaders in the hope that they would encourage women to participate—or at least not create more hurdles. 

The next issue was where to find screening centres. We used premises of local political parties, community halls, and even a church where our female healthcare workers could conduct clinical breast examinations. Screening 75 000 women and actively monitoring the other 75 000 in the control arm by way of home visits every two years was a mammoth task. Women would often move residence, and it was up to our medical social workers to trace them to their new address. Women would often be unavailable when our female healthcare workers and medical social workers visited, which then required multiple visits. From time to time, the Mumbai Municipal Corporation would decide to demolish a slum in order to redevelop it; as a result, several hundred women would suddenly disappear and had to be traced in other areas of the city. It was nothing short of a miracle that our medical social workers were able to trace them in their new homes and it is entirely to their credit that our overall compliance to screening was close to 70%—a very respectable achievement under the circumstances.

The female healthcare workers had to be trained to conduct clinical breast examinations, and their performance had to be evaluated at regular intervals for quality control. Then, when patients died, there was the problem of finding the cause of death. In addition to eliciting information from the Municipal Corporation and Bombay Cancer Registry, we often had to visit various hospitals and nursing homes in the city where the women might have been treated to determine what they had died from. 

The NCI funding dried up after 15 years, and we had not achieved the pre-stated figure of 230 deaths in the control arm when we could perform a formal analysis as mandated by the protocol. The trial had to be extended, which needed additional funding. Several corporate houses and philanthropic bodies generously contributed, which was supplemented by the support of intra-mural funds from our institute.

In the end, we pulled it off. Our results are published in The BMJ for readers to see. In retrospect, it was our passion for science and naïve self-confidence that gave us the strength to continue with this study. Finally, and lest we forget, the ultimate thank you must be reserved for our female healthcare workers and medical social workers and the study participants. We are grateful to them for their selfless dedication and commitment to the goals of the trial; we salute them for the successful end to the study. 

Indraneel (Neel) Mittra is a breast cancer surgeon, a laboratory scientist, and a public health researcher. Currently he is Dr Ernest Borges chair in translational research and professor emeritus, Department of Surgical Oncology, Tata Memorial Centre, Mumbai.

Competing interests: I declare support from the US National Institutes of Health, Tata Memorial Centre, Sir Dorabji Tata Trusts, M K Tata Trusts, Department of Atomic Energy (Government of India), and the Women’s Cancer Initiative, India for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.