People worry about cancer. It remains one of the scariest diagnoses because treatment can be harrowing and the outcome uncertain.
Millions of Americans try to avoid unnecessary exposure to carcinogens (cancer-causing chemicals). That's why they spend more to buy organic food.
Many people don't realize, however, that some of the pills they take every day might be carcinogens. The Food and Drug Administration requires drugs to be screened for cancer-causing potential before approval. It may come as a surprise that many medications on the market can cause cancer in some animal tests.
Even more disquieting, studies of certain drugs have raised red flags about cancer in humans. One of the most recent involves a popular diabetes drug called Actos. More than 11 million prescriptions for it were dispensed last year.
The FDA has just notified the public that taking Actos for more than a year may be associated with an increased risk of bladder cancer. French authorities have taken Actos off the market due to concerns raised by epidemiological studies. German regulators told doctors not to start any more patients on the drug.
In the United States, doctors have been given limited advice about how to use this scary information. The FDA advises them not to prescribe Actos to patients with bladder cancer and to encourage patients to report symptoms such as painful urination, blood in the urine or urinary urgency.
This is not the first time physicians and patients have been left in a quandary about drugs that might cause cancer. Powerful immune-modulating drugs such as Enbrel, Humira and Remicade also are under scrutiny. These medications are very helpful for patients with rheumatoid arthritis, Crohn's disease and hard-to-treat psoriasis.
The trouble is that these drugs have been associated with certain cancers such as lymphomas, leukemias, melanoma, leiomyosarcoma, kidney and liver cancer. Weighing the benefits and risks of such drugs becomes very challenging. Many people with rheumatoid arthritis couldn't function without the relief these drugs provide.
The decision may be even more difficult in certain other conditions. Eczema (atopic dermatitis) can make life miserable. It is characterized by red, itchy, flaky skin that overreacts to irritants.
Topical immune-suppressing treatments, such as Elidel and Protopic, control eczema symptoms quite nicely. But the black-box warning in the prescribing information can be distressing to patients: "Although a causal relationship has not been established, rare cases of malignancy (e.g., skin and lymphoma) have been reported in patients treated with topical calcineurin inhibitors [Elidel and Protopic]."
Because cancer often takes many years to develop, there are few good studies that can provide definitive answers on this issue. It took decades and an enormous clinical trial (the Women's Health Initiative) to reveal a clear connection between postmenopausal hormone use and the risk of breast cancer.
When the FDA issues a warning such as the one about Actos, millions of people with diabetes are left wondering if their drug might pose a cancer risk. The agency should require drug companies to follow up on such studies and clarify the risk so that doctors and patients can make better-informed decisions.