bcl-2/bax Ratio a Marker For Response to Radiotherapy for Prostate Cancer

January 22, 1999. Markers for predicting therapeutic response of prostatic tumors to radiotherapy would be helpful in optimizing effective treatment of prostate cancer. Some cancer cells are resistant to radiotherapy, causing the treatment to fail.
    A research team from the Department of Surgery at University of Maryland School of Medicine set out to see if there is a correlation between "the ratio of two apoptosis regulators, bcl-2 (apoptosis suppressor) and bax (apoptosis inducer) in prostatic tumors and the clinical response to radiotherapy in patients with localized prostate cancer." (Aptoptosis is the process of programed cell death.) They report in the journal Urology that indeed there does seem to be a link.
     They reviewed records of 41 patients who underwent external beam radiotherapy for prostate cancer. On the basis of post-treatment prostate biopsy and prostate-specific antigen (PSA) criteria, they classified the cancers of 20 patients as radiation nonresponders and 21 as radiation responders. By analysing biopsy sections for each patient, they found the level of expression in the patioent's tumor cells of the two apoptotic proteins, bcl-2 and bax.
     The study found that bcl-2 was significantly higher in prostatic tumors not responsive to radiotherapy compared with the radiation responders. Expression of bax protein was lower in nonresponders, but values were not significantly different from the responders. The researchers say that a high bcl-2/bax ratio (P <0.01) "correlated with poor therapeutic responsiveness of prostate cancer to radiotherapy." They add that this was independent of age, PSA, and Gleason score.
     The researchers say that their findings suggest that patients with an elevated bcl-2/bax ratio are at increased risk of their cancer failing to respond to radiotherapy. They see value for the bcl-2/bax ratio as a potential molecular marker providing a test to see whether a patient with prostate cancer is liable not to benefit from radiotherapy.

Urology 1998 Dec;52(6):1085-90
bcl-2/bax ratio as a predictive marker for therapeutic response to radiotherapy in patients with prostate cancer.
Mackey TJ, Borkowski A, Amin P, Jacobs SC, Kyprianou N
Department of Surgery, University of Maryland School of Medicine, Baltimore

Upfront	Medical Pike	Voices	EatingWell	Grassroots	Caplinks