Magazine article Science News

Ovulation Cycles Linked to Ovarian Cancer

Magazine article Science News

Ovulation Cycles Linked to Ovarian Cancer

Article excerpt

For the female body, ovulation is hard work. An ovary secretes hormones, produces an egg, thrusts it through a wall of tissue, and afterward repairs the rupture. Four weeks later, the process repeats.

Scientists have suspected that the frequency and rigor of tissue rebuilding can lead to ovarian cancer because, after each ovulation, the manufacture of new cells requires synthesis of DNA. This cell proliferation is thought to open the door to mutations in the p53 gene, which produces one of the body's natural cancer fighters.

Now, a new study bolsters this incessant-ovulation theory (SN:10/31/92, p. 298) and its corollary that pregnancy, breast feeding an infant, or taking oral contraceptives lessens a woman's cancer risk by giving her welcome rests from ovulation and easing wear and tear on the ovaries.

The key element in this theory is the p53 gene, which normally blocks cell division when a cell has sustained DNA damage. If the p53 gene itself becomes disabled, however, it allows damaged cells to proliferate, possibly leading to cancer. A sure sign of a mutated p53 gene, researchers have discovered, is overproduction of a distorted p53 protein.

Duke University researchers tested for overproduction of altered p53 protein in malignant tissue from 197 women, averaging 47 years old, with ovarian cancer. They found that 105 had such an overabundance. Moreover, the researchers calculated that these 105 women each averaged 388 ovulation cycles in her life so far, nearly 30 full years' worth, while the ovarian cancer patients without the p53 protein surplus averaged only 342 cycles.

Compared with a group of 3,363 healthy women, the women who had cancer and an overabundance of the telltale p53 protein were nine times more likely to have had high numbers of ovulation cycles. This difference emerged after the researchers statistically accounted for variations in age, menopausal status, and number of children, says Joellen M. …

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