Prostate cancer is one of the most commonly diagnosed tumors in the US, with an estimated 233 000 new cases diagnosed in 2014.
Active surveillance (AS) is a treatment method whereby the course of the cancer is monitored carefully, with an expectation to start treatment immediately if the cancer is found to progress. AS is currently considered for prostate cancer patients who have a life expectancy of at least 10 years and whose disease is considered to be low-risk.
In the study, published in JAMA Oncology, the researchers state that no direct comparison has been made between low-risk prostate cancer and favorable intermediate-risk prostate cancer pertaining to rates of prostate cancer-specific and all-cause mortality following courses of high-dose radiotherapy.
Such a comparison is relevant, according to the study authors, as AS is currently only considered appropriate for patients with low-risk prostate cancer per the guidelines of the National Comprehensive Cancer Network (NCCN).
If patients with favorable intermediate-risk prostate cancer have rates of prostate cancer-specific and all-cause mortality comparable to those experienced by patients with low-risk prostate cancer then AS could also be an appropriate form of treatment for them, allowing these patients to avoid the clinical risks that come with brachytherapy - a form of high-dose radiotherapy.
Currently, radiation therapy is the most common form of treatment for patients with all forms of prostate cancer. Another new study, also published in JAMA Oncology, reports that around 57.9% of prostate cancer cases are treated with radiation therapy, whereas only 9.6% of cases are treated with watchful waiting or AS.
"There remains an increased use of treatments in men diagnosed as having prostate cancer and underuse of active surveillance in men with low-risk disease. There is an increased use of radiotherapy among all risk groups and in particular patients with indolent disease with limited correlation according to tumor biological characteristics and patient health," state the authors.
'Similarly low mortality estimates' observed following brachytherapy
For the study concerned with the implications for AS in men with favorable intermediate-risk prostate cancer, Dr. Ann C. Raldow and colleagues analyzed data for 5,580 men with localized prostate cancer that were treated at the Prostate Cancer Foundation of Chicago from 1997-2013.
They calculated the estimated risks of prostate cancer-specific and all-cause mortality following brachytherapy and compared findings for patients with low-risk prostate cancer with those for patients with favorable intermediate-risk prostate cancer.
A total of 605 patients (10.84%) died during the follow-up period. Among these, 34 patients (5.62% of total deaths) died specifically due to prostate cancer. Overall, the authors report that the men with favorable intermediate-risk prostate cancer did not have a significantly greater risk of mortality compared with men with low-risk prostate cancer.
Specifically, 8-year estimates for prostate cancer-specific mortality were 0.48% for men with favorable intermediate-risk prostate cancer, compared with 0.33% for men with low-risk prostate cancer. Similarly, for all-cause mortality, the estimate was 10.45% for men with favorable intermediate-risk prostate cancer and 8.68% for men with low-risk prostate cancer.
"Despite potential study limitations, we found that men with low-risk prostate cancer and favorable intermediate-risk prostate cancer have similar and very low estimates of PCSM [prostate cancer-specific mortality] and ACM [all-cause mortality] during the first decade following brachytherapy," report the authors.
The authors urge that their findings should be interpreted with caution as they are based on data taken from a single institution and were not obtained from a randomized clinical trial. However, they also note that a randomized trial of AS against treatment is currently being conducted in the UK.
In a related commentary, Dr. Fred Saad of the University of Montreal, Canada, suggests that these findings require careful reflection:
"Although I am a urologist who has been practicing active surveillance for most of my low-risk patients for many years, I suggest that we continue to be very cautious, and extremely selective, in offering AS to patients with any features of intermediate-risk prostate cancer."
At the end of last year, Medical News Today reported on a study suggesting that physical activity is linked to a lower risk of death in patients with localized prostate cancer.