Why prostate cancer returns in some patients

Washington, May 28 (ANI): A new study has shed new light on why prostate cancer returns in some men despite receiving surgery or radiation therapy.

While most men have an excellent outcome with such standard treatments for localized prostate cancer, there are some for whom the treatment isn't really effective.

The study is a collaborative effort between researchers at the Josephine Ford Cancer Center at Henry Ford Hospital and Fox Chase Cancer Center.

And it found that men with a low oxygen supply to their tumour are at a higher risk of prostate cancer return, if the prostate-specific antigen (PSA) levels were increased after treatment.

"After several years of research, we were able to show that low levels of oxygen to the tumour are highly related to a patient's outcome. Those with lower oxygen levels to the prostate cancer did not respond as well to radiation therapy, and the cancer returned more often," said Dr. Benjamin Movsas, senior study author.

Recent studies have shown that the same applies to patients treated with surgery.

Movsas said that oxygen delivery to a tumour is critical to the treatment for many cancers- for example, radiation therapy creates free radicals that damage DNA in tumours, and oxygen acts as the mediator that perpetuates the free radicals.

Thus, Movsas began his work nearly a decade ago to investigate low oxygen levels - also known as tumour hypoxia - in prostate cancer tumours while working at Fox Chase.

To measure the amount of oxygen being delivered to the tumours and surrounding areas, researchers used custom-made oxygen probes to test 57 patients with low or immediate risk of cancer prior to radiation therapy.

The probe was used prior to "radioactive seeds" which were implanted in the prostate.

The initial study found that it is possible for prostate cancer tumours to have low oxygen levels.

And now, they have revealed that a tumour's oxygen supply can significantly predict a patient's outcome following treatment, independent from tumour stage or Gleason score-a classification of the grade of prostate cancer.

Of the 57 patients, the study found that eight experienced an increase in their PSA levels about eight years following treatment.

The results from the study will be presented at the American Society of Clinical Oncology (ASCO) annual meeting in Orlando. (ANI)