Breast cancer is a cancer of prosperity: Mary-Claire King

Updated - February 23, 2017 08:08 am IST

Published - February 23, 2017 12:25 am IST -

A few decades ago, when the predominant belief was that breast cancer was caused by viruses and when DNA sequencing technology was yet to be discovered, Dr. Mary-Claire King proved that the disease was linked to genetic mutations. It took Dr. King — who is currently Professor Genome Sciences at the University of Washington — 15 years to build a mathematical model to support the hypothesis. In the 1990s, she and her team identified the BRCA1 gene, popularly called the breast cancer gene.

Prof. King was in the city on Wednesday to give a lecture — Understanding Inherited Breast and Ovarian Cancer: From Gene Discovery to Precision Medicine and Public Health — for the seventh edition of the Cell Press-TNQ India Distinguished Lectureship Series, 2017.

She opened with a chart showing incidence rate of breast cancer in Bengaluru from the late 1980s to the present. The shape of the curve goes up rapidly, compared to the incidence rate of cervical cancer which is dropping. This kind of pattern is reflected everywhere in the world, but Bengaluru’s curve is one of the steepest.

“Breast cancer is uniquely a cancer of prosperity. It’s a cancer of women who are educated and consequently decide to postpone having their children. Of young girls who are well-nourished and consequently begin menstruation or menarche at a younger age,” she said, adding that the interval between the age of menarche and the age of first pregnancy is now three-four times longer than it was a 100 years ago. “And the link of that interval has been shown by epidemiological studies worldwide to be primary determinant of breast cancer risk,” she said.

While incidence of breast cancer is higher in the European Union and the U.S. when compared with India, the mortality rates are “not that dissimilar”. “This is because survival is poorer here because breast cancer still presents itself in India at considerably later stages,” she said.

She underscored the importance of identifying and screening women above the age of 30 who were at the very highest risk of developing breast and ovarian cancer. Breast cancer when detected at its later stages, is much harder to eradicate. The best way to combat this is through genetic to see if a person is predisposed to mutations.

But will India rise to this challenge? Screening does not come cheap, and will be a burden on the country’s healthcare, but Prof. King expressed confidence in the technologies coming out of India that will reduce costs. “If we are in a resource-limited environment, we can focus the resources that there are on people for whom they will have the greatest yield,” said Prof. King.

At the lecture, the finalists for the Inspiring Science Award for the best published scientific paper in the Life Sciences from India were also announced.

Breaking barriers

When Dr. Mary-Claire King shifted her focus from mathematics to genetics at the University of California, Berkeley, more than four decades ago, the field of science was as much a testosterone-filled male dominated bastion as a male locker room. After she accepted a position in the School of Public Health at her alma mater, the epidemiology division head said to her, “I just want you to know that you are only here because of all these new regulations, and we are really scraping the bottom of the barrel in hiring you.” Her reply was a succinct, “We’ll see how long you feel that way.” And she did just that.

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