Revolutionizing Metastatic Prostate Cancer Treatment with Targeted Therapies

Among Canadian men, prostate cancer is the single most common cancer. Most cases of prostate cancer are relatively low- risk, but some will become metastatic and progress into life-threatening illnesses. Prostate cancer remains one of the top causes of cancerrelated death in the world, claiming the lives of thousands of Canadian men every year. New treatments that can extend life, and most especially improve the quality of that extended life, are therefore very welcome.

“Patients diagnosed with localized prostate cancer have a very high chance of either being cured or not needing any treatment at all,” says medical oncologist Dr. Urban Emmenegger of Sunnybrook Health Sciences Centre’s Odette Cancer Centre. “But 20 to 30 percent of patients will, at some point, develop metastases. When that happens, they’ll usually go on androgen deprivation therapy. This works for almost all patients, for a time averaging around two years but varying considerably from patient to patient. After that time, the cancer often becomes active again, and that’s when the clock really starts ticking in terms of prognosis.”

More life and better life

Prostate cancer in this stage, where it has metastasized to other parts of the body and become resistant to androgen deprivation therapy, is referred to as metastatic castration- resistant prostate cancer ( mCRPC). This type of cancer is usually fatal, but this only makes effective treatment more vital. For men with this condition, an extra year or two of life is of incalculable value, and especially so if the treatment needed during that time is easier to tolerate than chemotherapy, allowing patients to live their lives as they wish.

With the introduction of a new generation of oral therapies that provide superior cancer control with less toxicity and fewer side effects, this is finally becoming a reality. “Until 2010, the only life-prolonging treatment available for mCRPC was intravenous chemotherapy,” says Dr. Emmenegger. “Since then, however, we’ve gained access to new oral treatments that have changed the prognosis significantly. In addition to slowing down the cancer, these treatments also help us delay the need for chemotherapy.”

Targeted therapy makes it easier to live a full life

These new treatments, collectively known as androgen receptor axis- targeted agents, work by making testosterone and other androgens, the food that prostate cancer thrives on, less available to the cancer cells. They’re remarkable not just for their effectiveness, but also for how easy they are to take and tolerate. “These are tablets that patients can take at home,” says Dr. Emmenegger.“Once they are stable on the treatment, many men can go on with their lives as though they didn’t have prostate cancer. And patients who are stable on these therapies generally need only return to their oncologist for a few monitoring visits each year.”

Like any medication, these therapies can have side effects, and the side effect profile is often the reason for choosing one oral therapy over another. “Overall, we know that patients who are on these medications do better than patients who are not,” says Dr. Emmenegger. “They have fewer cancer-related symptoms, they have fewer pain issues, and they’re able to be more active overall.”

And that’s what patients want: not just to live longer, but to be able to be active and involved in their lives during that time.“These drugs prolong the lives of patients by a year or even longer,” says Dr. Emmenegger. “And this is good- quality living.”

Once they are stable on the treatment, many men can go on with their lives as though they didn’t have prostate cancer.