Men diagnosed with hormone sensitive metastatic prostate cancer are offered ADT, androgen-deprivation therapy (also called hormone therapy), to slow the progression of the cancer.
They are prescribed this therapy, most commonly, after both a radical prostatectomy and radiation (including external beam radiotherapy, brachytherapy [seeds], proton-beam radiotherapy, and Cyberknife radiotherapy) have failed.
Sometimes, they are treated with continuous hormonal therapy and sometimes intermittent hormonal therapy.
The advantage of the intermittent therapy relates to quality of life issues: impotence, libido, energy/vitality, physical function, emotional function and expense.
If the effectiveness of both continuous and intermittent therapy was the same, – and, up until this study, evidence seemed to indicate they were, – many doctors were recommending and many patients were choosing intermittent therapy.
Now, at the end of a 17-year study* – the largest such study to date in men with metastatic, hormonesensitive disease – reported at the annual ASCO (American Society of Clinical Oncology) meeting, the findings show a difference.
“Survival with intermittent hormonal therapy is not comparable to continuous therapy for patients with metastatic prostate cancer,” Dr. Maha Hussain, said.
Dr. Hussain, lead investigator of the study, presented the results at the ASCO meeting.
“The finding is striking and surprising because it goes against the conventional belief based on all the trials that have been done thus far. The data are likely to change practice,” she said.
Dr. Hussain concluded from the study: “Survival with intermittent therapy is inferior to continuous therapy.”
The study did show a difference between outcomes in men with minimal and men with extensive disease.
The findings would seem to make decisions clear, at least for patients with minimal disease, but not for everyone.
And so begins the discussion and the debate. When some doctors and patients consider the cost of continuous therapy in terms of quality of life, they might be willing to discount what they consider to be small differences in overall survival.
The lead author on the quality-of-life study, Carol Moinpour, PhD of Fred Hutchinson Cancer Research Center, said their study concluded:
“At three months, the continuous treatment patients reported statistically significantly more impotence and lower libido than the intermittent-treatment patients and the findings continued through the nine-month questionnaire.”
In addition results indicated additional benefits in the intermittent approach for both physical and emotional function and overall feelings of energy and vitality.
The phrase “live longer or live better,” came from Dr. Ulka Vaishampayan, third author of the survival report of this study.
Making A Decision
But regarding the question of whether the quality-of-life differences are enough to consider intermittent therapy, her view was decisive.
“It is unlikely that this much of a difference in quality-of-life would warrant considering intermittent ADT,” she said.
She did qualify her statement by saying: “There are patients who have significant side effects and who cannot function on androgen blockade therapy and whom you would be forced to consider for intermittent therapy. At least, this study shows the possibility of improvement in quality of life fairly rapidly after discontinuation of continuous therapy.”
If a patient chose intermittent therapy, she would “discuss the pros and cons with the patient including how they are likely to compromise survival in the long run if they go with the intermittent program.”
Dr. Catalona’s Opinion
Dr. Catalona believes that the differences between intermittent and continuous hormonal therapy found in this study are relatively small.
He believes that the patient can make the decision for intermittent or continuous therapy safely after the doctor presents the pros and cons of each approach.
The patient also has the option of trying each form of treatment before making a final decision.
* Hussain, M et al, “Intermittent (IAD) vs. Continuous Androgen Deprivation (CAD) in Hormone Sensitive Metastatic Prostate Cancer (HSM1PC) Patients (pts): Results of S9346 (INT-0162) an International Phase III Trial.” American Society of Clinical Oncology Annual Meeting, June 1-5, 2012, Chicago. ClinicalTrials.gov identifier: NCT00002651