Prostate cancer tends to develop in men over the age of fifty and, although it is one of the most prevalent types of cancer in men, many men never have symptoms and die of other causes. On the other hand, more aggressive prostate cancers account for more cancer-related deaths than any cancer except lung cancer. About two-thirds of cases are slow growing, the other third are more aggressive and fast growing.
The decision to treat a tumor contained within the prostate is a trade-off between the risk and expected benefits, especially quality of life. More and more often physicians and patients are electing to do nothing but wait (and hopefully enjoy life) for slow growing tumors.
The decision to wait is a calculated risk. Urologists look at a number of factors in prostate cancer to decide how to treat (if at all) prostate cancer. These factors include:
- Gleason Score: score given to prostate cancer based upon its microscopic appearance. Cancers with a higher Gleason score are more aggressive and have a worse prognosis. The Gleason scores range from 2 to 10, with 10 having the worst prognosis.
- Core biopsies positive: usually urologists take 6-12 total biopsies at a time, called cores. The percentage of positive cores varies and often changes over time.
- PSA: a tumor marker that, taken with the other two factors above, may indicate prostate cancer. The higher the score, and the more rapidly it climbs, the worse the prognosis. It usually slowly increases over time in men with low-grade prostate cancer.
All of these factors, along with the presence or absence of cancer spread, change over time and influence whether or not an urologist and patient decide to treat the prostate cancer.
To give you an idea about how this works, if you took 20 men with low risk prostate cancer and do nothing but biopsy them again in a year, about 10% of the men will no longer have any cores positive. That’s right, about 10% of men will no longer have demonstrable cancer. However, most men will have either more cores positive or a higher Gleason score or higher PSA or all three.
This week, Drs. David Marshall, Sebastiano Gattoni-Celli and their colleagues from the Medical University at South Carolina published a study that reported administering vitamin D for a year, measuring cancer markers before and after. The results were astounding.
Marshall DT, et al. Vitamin D3 supplementation at 4,000 IU/day for one year results in a decrease of positive cores at repeat biopsy in subjects with low-risk prostate cancer under active surveillance. Journal of Clinical Endocrinology and Metabolism. 2012.
This study administered 4,000 IU/day of vitamin D for one year to 44 men. The scientists chose 44 men with low risk prostate cancer, so they chose 44 men with identical Gleason scores of 6, anywhere from 1-6 cores positive (out of 12 possible), and a PSA < 10.
Of the 44 men they followed, 60% showed a decrease in the number of positive cores or a decrease in their Gleason scores, or both. Only 34% showed an increase in the number of positive cores or an increase in their Gleason scores. 6% were unchanged over the year. PSA levels did not go up over the year. The authors classified 60% of the men as “responders” to vitamin D and 40% as “non-responders.”
Fifteen of the 44 men (34%) no longer had any cores positive. However, PSA did not go down so they may or may not still have prostate cancer. It also appeared that baseline vitamin D levels were important because men with higher baseline vitamin D levels had fewer cores positive for cancer and lower Gleason scores.
The authors report that the main problem with the study was the lack of a control group, other than historical groups of men treated conservatively. However, with 60% of the men responding to vitamin D, I wonder if an ethics committee would allow a randomized controlled trial, knowing some men in the control group would be vitamin D deficient.