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Does lung cancer kill more women than any other type of cancer? Add to ...

Question

Is it true that lung cancer kills more women than any other type of cancer? And why?

Answer

It is true. Lung cancer kills more women annually than breast cancer, colorectal cancer, or any other type of cancer. In fact, the Canadian Cancer Society estimates that 9,400 women will die from lung cancer in 2009, compared with 5,400 of breast cancer and 4,200 of colorectal cancer.

Here's what researchers are grappling with: Smoking rates are decreasing, yet the number of women being diagnosed with lung cancer is increasing. No one is sure why.

Part of it may be due to genetic factors. Scientists suspect that a gene in the X chromosome makes some people more susceptible to lung cancer, and since women have two X chromosomes, they may be twice as likely to carry that gene.

A woman's smaller frame may also contribute to increased susceptibility to the effects of tobacco carcinogens. Or, the issue might be one of hormones, which make women's bodies process smoke differently than men's.

And it's not just that more women are getting lung cancer - they also may not have the same symptoms as men.

For women, the cancer usually starts in the lung tissue as an adenocarcinoma, and there are generally no symptoms until the tumour is very large or has spread. Lung cancer in men will often start in the airways as a squamous cell tumour, causing "classic" symptoms such as a cough, coughing up blood or chest infection early on.

Traditionally, researchers didn't look at lung cancer from a gender perspective. In fact, studies to assess the usefulness of screening with X-rays and sputum were conducted predominantly on men. Findings from these studies suggested that screening is not an effective way to diagnose lung cancer because the male subjects were more likely to present with "classic" symptoms. Those results were assumed to apply to women, even though women's tumours are different and women are less likely to show "classic" symptoms.

But today's increasing focus on sex differences in health is leading scientists to think that screening may in fact be very helpful in diagnosing lung cancer in women.

Without screening guidelines, those diagnosed don't stand a very good chance of survival. Sadly, most die within a year of finding out they have the disease because their tumours are so large and advanced that they are not curable.

Early screening is the key to survival. If tumours are caught early enough, when they are still small, they can be surgically removed. If that happens, there can be a 95-per-cent five-year survival rate.

More discussion is needed. More resources for researching and developing new drug therapies are essential. Guidelines need to be created for when, where and how women should be screened for lung cancer. There needs to be a better understanding of how lung cancer affects women differently than men, and how we can treat, cure and help women survive this diagnosis.

If you're concerned about lung cancer, speak with your doctor. And remember, the best way to prevent lung cancer is to refrain from smoking.

Dr. Anna Day is the director of the gender and airways program at Women's College Hospital in Toronto.

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