GETTING PERSONAL: Individualized treatment for men with prostate cancer

An estimated 25,000 men are diagnosed with prostate cancer in Canada every year. A subset of these men with aggressive disease will require curative treatment with precisely-targeted radiotherapy. The Radiation Medicine Program (RMP) at the Princess Margaret Cancer Centre delivers state-of-the-art radiotherapy for prostate cancer, consisting of image-guided external-beam radiotherapy or low-dose rate or high-dose rate brachytherapy. These treatments are sometimes administered with systemic therapies, such as androgen deprivation therapy (to block the effect of testosterone). Choosing “the right treatment for the right patient at the right time” is an integral part of the personalized medicine that takes place at RMP and is based on patient factors and characteristics of the patients’ tumors (e.g. stage of disease, pathologic Gleason score, pre-treatment value of prostate-specific antigen).

JACQUES LUPIEN wanted cutting-edge radiotherapy for his prostate cancer after weighing his options between surgery and radiotherapy. With a localized tumor and more than 75% chance of cure, he opted for image-guided radiotherapy at the Princess Margaret and never regretted his choice. “When I needed treatment for prostate cancer, I sought a premium facility and hoped for a caregiver that I could relate to. Dr. Robert Bristow answered all my questions with patience and depth of knowledge. He insisted that with treatment the cancer would abate – and it did.”

Jacques’ case demonstrates the effectiveness of optimized therapy, but unfortunately due to microscopic disease outside the prostate gland and lymph nodes at the time of treatment, not all patients are cured by radiotherapy. Providing patients with more specific information about their chance for success with one therapy or another is the basis for personalized cancer medicine.

Personalized cancer medicine for prostate cancer is now entering a new era. Within the next 5 years, patients will be provided with the best treatment options determined by tests that define their unique cancer genetic fingerprints and measure the tumor microenvironment. RMP will be able to offer the best care for prostate cancer patients by understanding which therapies are the most successful for certain genetic subtypes.

In a landmark study published in Lancet Oncology last year, RMP researchers evaluated the role that prostate cancer cell genetics and tumor microenvironment play in predicting successful treatment with radiotherapy. Analysis of pre-treatment tumor biopsies for genetic aberrations and oxygen content revealed that patients whose tumors had similar clinical characteristics could be further subdivided into those that would, or would not, do well with precision radiotherapy. Men with low levels of genetic changes had a favorable outcome; therapy would be effective more than 95% of the time. Men with aggressive features characterized by high levels of genetic changes and low oxygen content (also called hypoxia; a predictor of spread in prostate cancer) had a 50% chance that the treatment would fail to control the tumor.

These results will be validated over the next two to three years on more patients before a personalized test to accurately predict prostate cancer recurrence can be utilized in the hospital setting. The clinical impact of such a test is significant and will benefit thousands of patients. It will provide a way to identify men who are at greatest risk of their prostate cancer returning and who could be offered more aggressive treatment as part of a personalized treatment plan, ultimately improving cure rates for this subgroup of patients. 

Written by Dr. Robert Bristow, Radiation Oncologist and Clinician Scientist for Connexions published by the Radiation Medicine Department of Princess Margaret Cancer Centre. Photos courtesy of Donna Santos Studios.