Women Take Pill, Men Get Cancer - Oral Contraceptive and Prostate Cancer

in environment, medicine

When women take oral contraceptive, why should men get prostate cancer? The new controversial paper is published in BMJ open access journal linking oral contraceptive use in the population with prostate cancer. 

Prostate cancer is a cancer in the prostate gland, a small, walnut-sized structure in a man's reproductive system. Prostate cancer is the third most common cause of death due to cancer in men.

According to the paper, use of the contraceptive pill is associated with an increased risk of prostate cancer around the globe.  Prostate cancer is the most common male cancer in the developed world and the use of the contraceptive pill has soared over the past 40 years, say the authors.

The research team from Princess Margaret Hospital, University of Toronto used data from the International Agency for Research on Cancer (IARC) and the United Nations World Contraceptive Use report to pinpoint rates of prostate cancer and associated deaths and the proportion of women using common methods of contraception for 2007. They then analysed the data for individual nations and continents worldwide to see if there was any link between use of the contraceptive pill and illness and death caused by prostate cancer.

Their calculations showed that use of intrauterine devices, condoms, or other vaginal barriers was not associated with an increased risk of prostate cancer.

But use of the contraceptive pill in the population as a whole was significantly associated with both the number of new cases of, and deaths from, prostate cancer in individual countries around the world, the analysis showed. These findings were not affected by a nation’s wealth.

The authors emphasise that their research is speculative and designed to prompt further consideration of the issues. As such, their analysis does not confirm cause and effect, and therefore definitive conclusions cannot be drawn, as yet.

But they refer to several recent studies which have suggested that oestrogen exposure may boost the risk of prostate cancer. Excess oestrogen exposure is known to cause cancer, and it is thought that widespread use of the Pill might raise environmental levels of endocrine disruptive compounds (EDCs) - which include by-products of oral contraceptive metabolism.

These don’t break down easily, so can be passed into the urine and end up in the drinking water supply or the food chain, exposing the general population, say the authors.

“Temporal increases in the incidence of certain cancers (breast, endometrial, thyroid, testis and prostate) in hormonally sensitive tissues in many parts of the industrialised world are often cited as evidence that widespread exposure of the general population to EDCs has had adverse impacts on human health,” they write.

ScienceDebate.com Editorial Note: The following information adapted from cancer.gov (in quotes) and an environmental journal, may be useful for our readers to better understand the above research report. If females who consume this estrogen derivative are not at a very high risk for cancer (as seen below), how is it possible that the "hypothesized" water contamination with oral contraceptives can promote prostate cancer? We would expect that the authors would have provided at least the level of water contamination by the estrogen derivatives, while making this claim. In addition, the review article mentioned below lists a number of sources other than oral contraceptives contributing to estrogen contamination of water. 

"Studies have consistently shown that using oral contraceptives reduces the risk of ovarian cancer. In a 1992 analysis of 20 studies of oral contraceptive use and ovarian cancer, researchers from Harvard Medical School found that the risk of ovarian cancer decreased with increasing duration of oral contraceptive use. Results showed a 10 to 12 percent decrease in risk after 1 year of use, and approximately a 50 percent decrease after 5 years of use."

"Currently, two types of oral contraceptives are available in the United States. The most commonly prescribed oral contraceptive contains two man-made versions of natural female hormones (estrogen and progesterone) that are similar to the hormones the ovaries normally produce. This type of pill is often called a “combined oral contraceptive.” The second type of oral contraceptive available in the United States is called the minipill. It contains only a type of progesterone.

Estrogen stimulates the growth and development of the uterus at puberty, causes the endometrium (the inner lining of the uterus) to thicken during the first half of the menstrual cycle, and influences breast tissue throughout life, but particularly from puberty to menopause.

Progesterone, which is produced during the last half of the menstrual cycle, prepares the endometrium to receive the egg. If the egg is fertilized, progesterone secretion continues, preventing release of additional eggs from the ovaries. For this reason, progesterone is called the “pregnancy-supporting” hormone, and scientists believe that it has valuable contraceptive effects. The man-made progesterone used in oral contraceptive is called progestogen or progestin.

Because medical research suggests that some cancers depend on naturally occurring sex hormones for their development and growth, scientists have been investigating a possible link between oral contraceptive use and cancer risk. Researchers have focused a great deal of attention on oral contraceptive users over the past 40 years. This scrutiny has produced a wealth of data on oral contraceptive use and the development of certain cancers, although results of these studies have not always been consistent. The risk of endometrial and ovarian cancers is reduced with the use of oral contraceptives, while the risk of breast and cervical cancers is increased."

According to a report appeared in the journal Environmental Science & Technology in Dec 2010,  contrary to popular belief, birth control pills account for less than 1 percent of the estrogens found in the nation's drinking water supplies, scientists have concluded in an analysis of studies published on the topic. This report suggests that most of the sex hormone -- source of concern as an endocrine disruptor with possible adverse effects on people and wildlife -- enters drinking water supplies from other sources.

Science Story Reference: 

Oral contraceptive use is associated with prostate cancer: an ecological study. David Margel, Neil E Fleshner. BMJ. November 17, 2011. doi:10.1136/bmjopen-2011-000311.

Additional Sources: 

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