Halving duration of ADT for high risk prostate cancer patients

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Published: 4 Jun 2017
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Prof Abdenour Nabid - Sherbrooke University Hospital Centre, Sherbrooke, Canada

Prof Nabid speaks with ecancer at ASCO 2017 about the non-inferiority of 18 months of androgen deprivation therapy to 36 months for high-risk prostate cancer.

Across multiple scales and points, Prof Nabid highlights the equal clinical outcomes, better patient quality of life and significant reductions in cost and toxicity for patients receiving the shorter course of ADT with initial radiotherapy.

Considering the time and resource investment in reaching these results, he describes further investigation to find a minimum dosage duration for equivalent outcomes as unlikely, especially considering the recent successes with abiraterone for prostate cancer.

These findings were discussed further by Prof Charles Ryan and Dr Chris Parker here.

For more prostate cancer updates, tune in to the ecancer prostate symposium.


ecancer's filming has been kindly supported by Amgen through the ECMS Foundation. ecancer is editorially independent and there is no influence over content.

My presentation was about the duration of androgen deprivation therapy in high risk prostate cancer. What we did, we did a phase III trial on 630 patients and we compared 36 months of androgen deprivation therapy to 18 months. This trial will report the results with a median follow-up of 9.4 years and we didn’t find a difference in overall survival between the two arms which were compared. We had other primary endpoints like quality of life; we used two validated tools from the EORTC group, EORTC30 and PR25, and we found that the 18 months group of ADT had a better quality of life. We found that thirteen items and six scales had a p-value less than 0.01, a very significant p-value. We have found also that for hot flushes and enjoyable sex, two items with highly significant p-values, we had also main score differences over ten points. These data for quality of life are very long-term data, we have quality of life data over eight years for both groups. So we didn’t find for disease survival, disease specific survival, if we take into account deaths due to prostate cancer there is no difference.

We found also for secondary endpoints, the only difference we found was for biochemical failure with the definition of PSA [?? 1:58] plus two. What we found is that for the longer course of ADT, 36 months, we found a significant p-value over 18 months. But it didn’t translate into a better control of the tumour. We had 83 men with prostate cancer recurrence, 40 in arm one and 43 in arm two, and the rate of metastasis, bone metastasis alone or bone metastasis associated with other metastasis, is really the same. So this difference in biochemical failure didn’t translate into a better control of the tumour.

We had also the disease free survival, taking into account biochemical failure, progression of prostate cancer and death from any cause. In disease free survival, even if the two curves separate because of a better biochemical control in the 36 months group, the p-value was not significant. We did also a univariate and multivariate Cox regression analysis taking into account the duration of androgen deprivation therapy, age, disease at entry, PSA score, PSA Gleeson score and stage and also during follow-up biochemical failure. The only two variables which had significant p-values were age and Gleeson score, no other significant variables and we are talking especially for biochemical failure.

So, in conclusion, we think that we can safely reduce. We are talking of localised high risk prostate cancer treated with radiotherapy and androgen deprivation therapy. We can reduce the duration safely, the duration of androgen deprivation therapy, from 36 to 18 months. What we think is that probably 18 months of androgen deprivation is sufficient; it’s like a threshold effect – you can pour more androgen blockade after, you are not going to change the outcome. You really have a better quality of life for sure and also you can reduce the side effects and the costs. So we think that 18 months represents really a new standard of care for this population. Thank you.

If 18 months is no different from 36 months would there be any sense in an exploratory trial to find out if maybe 15 months or even 12 months? Where is the lowest threshold that you mentioned? If there’s no difference to 18 to 36, why not find the minimum time?

There is a trial done by the EORTC, they compared 6 to 36 months and the trial was negative – 36 months was better than 6 months of ADT. So you are talking of doing a trial in between. It takes us twenty years from the concept of the trial, we started to recruit the patients seventeen years ago and now we have data with close to ten years median follow-up. So if you want to repeat this trial you are going to get the response, maybe if you are lucky, in fifteen years. What we saw during this ASCO meeting is that there are probably other ways to have a better return on our work, like the study we are looking for this group of patients adding chemotherapy or adding abiraterone. This is the future for trials, going this way, not repeating the trial we did, it’s just too long. If really you downsize the duration of ADT for this group of patients, what we did twenty years ago, we had the idea to cut by half the duration. That’s enormous for the patients, for the side effects, that’s really enormous. I don’t think this trial will be repeated in the future. We are going to live with these results.

You mentioned the savings for cost, the improvement to quality of life.

For sure. What we did, and this was not reported yesterday, but we have a solid database about testosterone recovery in these patients. This will be part of the manuscript and what we saw is that there is a faster testosterone recovery in the 18 months group and for more patients too. So this could explain also the quality of life data.