Around 220,800 men in the US will be diagnosed with prostate cancer in 2015.
Researchers from Brady Urological Institute at John Hopkins University in Baltimore, MD, analyzed data on long-term survival outcomes for 1,298 men with prostate tumors classified as a low or very low risk for aggressiveness.
Study author Dr. H. Ballentine Carter, professor of urology at Johns Hopkins School of Medicine, says:
"Our goal is to avoid treating men who don't need surgery or radiation."
The research team found that men were unlikely to develop metastatic prostate cancer or to die from their cancer if their prostate tumors were relatively unaggressive, so long as urologists carefully monitored the disease.
According to the results of the study, only two of the 1,298 men died of cancer and only three developed metastatic disease over a 15-year follow-up period.
Of the two men in the active surveillance program who died of prostate cancer, one did so after 16 years. The second, after a recommendation to take part in active surveillance, sought monitoring at another hospital; he died 15 months after his diagnosis.
Of the 47 who died of non-prostate cancer causes, mostly cardiovascular disease, nine had received treatment for their prostate cancer. After 10 and 15 years of follow-up, survival free of prostate cancer death in the group was 99.9%, while survival without metastasis was 99.4%.
Those in the program, the research concludes, were 24 times more likely to die from a cause other than prostate cancer over the 15-year follow-up.
Risk of lethal prostate cancer 'no more than 5.9%' for men with low-risk tumors
For the study, urologists performed annual biopsies on all the men in the study group until the age of 75. Today, doctors only undertake biopsies among the riskier groups. When they do perform one, they use MRI (magnetic resonance imaging)-guided technology. Pathologists then check biopsy tissue for biomarkers of prostate cancer aggressiveness - proteins made by the PTEN gene.
"The ability to identify men with the most indolent cancers for whom surveillance is safe," says Dr. Carter, "is likely to improve with better imaging techniques and biomarkers."
The researchers reclassified 36% of the study participants to a more aggressive prostate cancer grade within 2 years of enrollment to the active surveillance program.
For men with very low-risk cancers - which would have usually precluded enrollment in the program - the cumulative risk of a grade reclassification was as follows:
- Over 5 years - 3%
- Over 10 years - 21%
- Over 15 years - 22%.
For men with low-risk cancers, the risk of grade reclassification was:
- Over 5 years - 19%
- Over 10 years - 28%
- Over 15 years - 31%.
The study reveals that the cumulative risk of a grade reclassification to a level that would be considered potentially lethal in most cases, but still curable, was no more than 5.9% for both very low and low-risk prostate cancers.
Despite the absence of significant change in their prostate cancer status, 109 men opted for surgical or radiation treatment. Among those whose cancers were reclassified, 361 opted for treatment.
"There is a careful balance, which is sometimes difficult to find," Dr. Carter says, "between doing no harm without treatment and overtreating men, but our data should help."
"Our study should reassure men that carefully selected patients enrolled in active surveillance programs for their low-risk prostate cancers are not likely to be harmed by their disease."
Dr. Carter warns that the study outcomes may be a result of two factors: the careful selection process for active surveillance and that no African-American men, who tend to have more aggressive cancers, took part.
The study reveals that as many as 80% of men in Scandinavian countries opt for active surveillance, compared with 30-40 % of US men. Dr. Carter says that the reasons for lower use of active surveillance in the US may stem from fear of losing the opportunity for a cure.
The study concludes that a urology specialist should monitor men with low-risk prostate cancer in an active surveillance program. Best practice guidelines for doctors, developed by the National Comprehensive Cancer Network - a group of the top cancer centers in the US - recommend such active surveillance.
In July, Medical News Today reported on a study suggesting more men with localized low-risk prostate cancer are engaging in "watchful waiting" for the management of their condition rather than opting for aggressive treatment.