Tuesday, November 15, 2011

Rise in prostate cancer 'due to use of the Pill which increases men's exposure to oestrogen' (?)

This is a bit puzzling. Antiandrogens are commonly used as a treatment for prostate cancer -- so one would expect estrogens to suppress rather than amplify prostate cancer.

But the findings are a lot of epidemiological speculation anyway. A less specific but more defensible interpretation of the data would be to say that modernity -- or something unknown associated with it -- increases prostate cancer. Greater sexual activity? More hazardous sexual activity?

Increasing use of the contraceptive pill is being linked with the rise of prostate cancer in men. Researchers say the Pill has soared in popularity over the past 40 years, and at the same time prostate cancer has become the most common form of the disease in men.

There is a statistical relationship between the two trends, possibly driven by men’s greater exposure to the oestrogen hormone contained in the Pill.

Widespread use of the Pill has led to more of the hormone finding its way into the water supply and food chain, with implications for human health, says a study in BMJ Open.

Using data from 87 countries, researchers found that where the proportion of women using the contraceptive pill is higher, rates of prostate cancer are higher.

Other contraceptives such as intrauterine devices or condoms were not linked to a higher incidence of prostate cancer. A team of researchers from Canada used two sets of data to pinpoint rates of prostate cancer and associated deaths and the proportion of women using common methods of contraception for 2007.

Use of the contraceptive pill was significantly associated with the number of new cases of prostate cancer around the world, in findings which were not affected by a nation’s wealth and therefore probably not influenced by better detection through screening and health services.

The research is speculative and definitive conclusions cannot be drawn, said research leader Dr David Margel, of the Princess Margaret Hospital, Toronto University.

But excess exposure to oestrogen is known to cause cancer and the study suggests that widespread use of the Pill has resulted in by-products called endocrine disruptors being deposited in the environment.

These do not break down easily in the body so can be passed into urine and end up in the water supply or the food chain, thus exposing the general population.

Dr Kate Holmes, of The Prostate Cancer Charity, said: ‘This study does not present a strong evidence case for an association between the use of the contraceptive pill and prostate cancer, nor does it intend to.

‘It is intended to explore the possibility that release of endocrine disruptive chemicals (EDCs) into the environment, a process which is not unique to the Pill, might impact on the incidence of the disease.

‘However, for all of the 87 countries in the study, there is no information on the level of these chemicals in the environment, with the focus on the contraceptive pill as the sole source, which we know is not the case.’


Sitting for too long may raise cancer risk

The usual epidemiological overconfidence. I would interpret the findings as showing that people in poor health sit down more

More than 90,000 new cancer cases a year in the United States may be due to physical inactivity and prolonged periods of sitting, a new analysis shows.

The analysis, being presented today at the annual conference of the American Institute for Cancer Research in Washington, D.C., cites about 49,000 cases of breast cancer and 43,000 of colon cancer.

"This gives us some idea of the cancers we could prevent by getting people to be more active," says epidemiologist Christine Friedenreich of Alberta Health Services in Calgary, Canada. Calculations are based on U.S. physical activity data and cancer-incidence statistics. "This is a conservative estimate," she says. "The more physical activity you do, the lower your risk of these cancers."

Alpa Patel, an American Cancer Society epidemiologist who looked at the data, says the numbers "seem like very reasonable estimates."

Experts have known for years that physical activity decreases the risk of chronic diseases including cancer, heart disease, diabetes and obesity, Friedenreich says, but the new data give estimates on the number of cases that might be prevented if people were more physically active.

"A brisk daily walk of at least 30 minutes could lower a person's risk over time for breast cancer and colon cancer," says Alice Bender, a registered dietitian with AICR.

Friedenreich reviewed more than 200 cancer studies worldwide and found convincing evidence that regular physical activity reduces the risk of breast cancer, colon cancer and endometrial cancer by 25 percent to 30 percent. There's some evidence that regular exercise also reduces the risk of lung, prostate and ovarian cancer, she says.

Patel and others also have investigated the health dangers of sitting too long without moving around, which is called "sitting disease."

In a study of 123,000 people, she found that the more time people spent sitting, the higher their risk of dying early. "Even among individuals who were regularly active, the risk of dying prematurely was higher among those who spent more time sitting," she says.

Even if you are doing half an hour of aerobic activity a day, you need to make sure you don't sit the rest of the day, Patel says. "You have to get up and take breaks from sitting."

Emerging research indicates that prolonged sitting also increases the risk of some types of cancer, such as colon, endometrial and ovarian cancers, Friedenreich says.

James Levine, a professor of medicine at Mayo Clinic in Rochester, Minn., says many people sit an average of seven to 9 1/2 hours a day. "If you've sat for an hour, you've probably sat too long," he says.

Friedenreich is looking into why exercise reduces cancer risk. In a study of 320 postmenopausal women, she has found that physical activity appears to decrease the risk of cancer by increasing insulin sensitivity and reducing body fat, inflammation, metabolic hormones and sex-steroid hormones.


1 comment:

Anonymous said...

The Prostate Cancer rate may be effected by the pill article doesn't address longevity. For prostate cancer it's been said that it's not a case of if a man will get it but when so the first item of correlation may be in the life expectancy of men in the countries with the greater incidence of prostate cancer.