Prescription for cancer?

The side effects of medications are probably one of the main barriers to successful treatment and compliance. Ideally, the risks and benefits of prescription medications should be weighed prior to exposure to the chemicals they contain – will they do enough good for the ailment while doing less, and acceptable, harm. This varies among patients, but some common threads may underlie these choices, such as whether a risk of malignant cancer is acceptable when treating a mild and/or non-lethal condition. Some prescription drugs do have known or assumed cancer risks, yet others have risks that were missed upon review for approval to sell them. Some with concerns are hormone replacement, eczema creams, rheumatoid arthritis injections, and cholesterol lowering drugs.

The side effects of medications are probably one of the main barriers to successful treatment and compliance. Ideally, the risks and benefits of prescription medications should be weighed prior to exposure to the chemicals they contain – will they do enough good for the ailment while doing less, and acceptable, harm. This varies among patients, but some common threads may underlie these choices, such as whether a risk of malignant cancer is acceptable when treating a mild and/or non-lethal condition. Some prescription drugs do have known or assumed cancer risks, yet others have risks that were missed upon review for approval to sell them, some of which Consumer Reports dubbed the “dirty dozen” in 2006. Yet others are mistakenly attributed to cancer risk that is not present in humans.

Creams for eczema

Elidel cream (pimecrolimus) and Protopic ointment (tacrolimus) are topical immunosuppressants used to treat the skin condition eczema. The FDA warns that these treatments do have a history of adverse reports of skin cancer and non-Hodgkin’s lymphoma. The manufacturer is currently carrying out trials to confirm or refute a potential link. According to WebMD, the FDA blackbox warning was placed on the two products in 2005 after being linked to 25 cases of cancer in children and adults. The products should be used only for the short-term and not in children under 2 years of age.

Hormone replacement therapy

Hormone replacement therapy is a treatment for the symptoms of menopause. The treatment is based on the idea that reduced estrogen level in the woman’s body leads to the uncomfortable symptoms, so replacing the hormone should ease them. One problem though – long-term estrogen therapy has been associated with increased cancer risk. According to the National Cancer Institute, at least two large-scale studies have been stopped early, one in 2002 when the risks of Prempro (estrogen plus progestin) were found to outweigh the benefits, and one in 2004 when estrogen alone caused cardiovascular problems. While estrogen plus progestin is protective against colorectal cancer, the treatment increases the risk of breast cancer. This breast cancer risk can be avoided by taking estrogen alone, but then the colorectal protection is lost and the estrogen only treatment increases uterine cancer risks according to the American Cancer Society. The good news is that stopping treatment allows the risk to dissipate over the following 5 years.

Rheumatoid arthritis injections

According to the NYTimes, in 2008, the FDA reported that they would review four drugs used to treat rheumatoid arthritis (with some success in Crohn's disease), Cimzia, Enbrel, Humira, and Remicade, due to reports of at least 30 cases of cancer associated with their use in children and young adults.  The drugs block tumor necrosis factor (TNF) alpha, an inflammatory chemical in the immune response. Blocking the immune response may increase lymphoma risk, both Hodgkin’s and non-Hodgkin’s forms, particularly in children. No cancer was seen in the clinical trials leading to Enbrel’s approval, so review is ongoing.

Cholesterol lowering drugs

In 1996, a review of previous studies on statins and fibrates (published in the Journal of the American Medical Association, JAMA) found that they consistently cause cancer in rodents, in some cases at doses nearly equivalent to those in humans. However, the data on cancer risk in humans was inconclusive and the researchers noted that rodent risk is not the same as human risk. Since that time, though, these drugs have been one of the prime examples of risky prescriptions. More recent studies have shown that statins may actually be protective against cancer, though the findings from a study on the protective effect of statins and fibrates against melanoma, an aggressive skin cancer, were not conclusive. Unlike other drugs in its class, lovastatin did show a significant protective effect against melanoma in that same study, indicating that the initial fears in the 1990s were unfounded.

However, in 2008, another kind of cholesterol-lowering drug, Vytorin, was found to increase cancer risk. As reported in the NYTimes, the study was one of three to study the interaction, but the only one to identify such a risk. Vytorin combines Zocor (simvastatin) and Zetia (ezetimibe) in a single pill. The risk seemed to be based on ezetimibe, as simvastatin has decades of research indicating no cancer risk. Two larger trials were set to be carried out, with early results in 2009 indicating no cancer risk from Zetia.

Other information

Other prescription drugs have shown tumor growth in rodents but without any cases in clinical trials. Yet others have been accused of causing cancer without any studies to prove these statements. Ultimately, it is important for any potential patient to read the warnings and precautions that accompany every prescription and ask a doctor for guidance if concerned.