Low T in Lung Cancer: Treatment Toxicity, Tumor-Related or Things otherwise
Michael Fisch, M.D.
Have you noticed how often the media and online world is bombarding you with information about testosterone?
Whether it is a reference to banned substances used by athletes, something that men wish they had more of in their aging bodies, or something having to do with the biology and treatment of cancer, it seems to happen with increasing frequency.
This week, in the journal Cancer another angle on the testosterone story comes forth--the idea that testosterone deficiency can result as the unintended and surprising consequence a new and effective cancer treatment. Specifically, researchers from the University of Colorado found that crizotinib, the new pill approved by the FDA, because it effectively treats the small subset of non-small cell lung cancer patients (4-7% of patients) who have a specific molecular aberration in the ALK gene, causes rapid suppression of testosterone levels. Those levels come back to normal when the crizotinib is stopped.
Here are 4 things that you might want to know to understand this testosterone issue in a broader context:
What can low testosterone do to a man?
You may already know this from all of those "low T" commercials on TV. Low T can cause reduced sex drive, poor erections, decreased energy, body changes, and mood changes.
Why do we care about testosterone in cancer care?
Testosterone and its receptors are part of a signaling pathway that can fuel the growth of certain tumors. Disrupting this pathway is thus an angle for treatment or prevention of those tumors.
The best example is prostate cancer, where removing the testicles or using hormone injections eliminates testosterone and treats prostate cancer, and the new drug abiraterone acetate works through blockade of the testosterone (androgen) receptor. More recently, at the annual Society of Surgical Oncology meeting on March 23rd, researchers from the Mayo Clinic in Arizona found that testosterone's receptor was found in 22% of breast cancers that don't express the other common receptors in that disease (so-called "triple negative" breast cancer). Perhaps this finding will lead to some new approaches to treat this specific form of breast cancer.
What impact does lowered testosterone actually have on advanced cancer patients? The short answer here is "we don't know for sure." In a review published in Lancet Oncology in 2010, 6 studies of this condition in men with advanced cancer were systematically reviewed, and it was not clear whether there are definite nutritional, functional, or quality of life characteristics attributed to the low testosterone in these men.
In men with cancer, there are other factors that cloud the picture which include the effects of the cancer itself, other side effects of cancer treatment, the effects of aging itself, and the influence of other health conditions and other kinds of medicines. In other words, it can be difficult to know exactly how to attribute the common symptoms that occur in men with advanced cancer that might also be due to low testosterone.
What should be done if you have cancer and low testosterone? This is another important question without a clear answer. As you might guess, if it's difficult to know what impact the low testosterone has on a person's quality of life, it's even more difficult to demonstrate the impact of treating affected men with testosterone replacement in the form of patches or muscle injections. This also brings up the controversial issue of how to measure the testosterone levels and decide what cutoff of "low" is meaningful and might trigger treatment. This is an issue that one should "T-up" for discussion with the doctor.