At 10 years, the risk of distant metastasis was 0.6%.
Researchers at Memorial Sloan Kettering (MSK) Cancer Center showed that active surveillance with a well-defined monitoring plan is a safe approach for appropriate patients with low-risk prostate cancer.
In the MSK retrospective analysis of over 2600 men who received active surveillance, there were 5 men who developed distant metastasis. The investigators concluded that only 2 of these patients had cancer that immediate initial treatment might have cured. At 10 years, the risk of distant metastasis was 0.6% (95% CI, 0.2-2.0).
“We have demonstrated that active surveillance is a safe management strategy at a tertiary cancer center when patients are appropriately selected and a well-defined monitoring plan is followed, in particular for men with very low risk prostate cancer. The long-term risk of metastasis is very low. The current study confirms prior reports demonstrating a low incidence of oncologic events in men with low-risk prostate cancer on active surveillance,” first study author Sigrid Carlsson, MD, PhD, and coinvestigators wrote in their study, which was published in the Journal of Urology.
Using the prospectively maintained database of patients with prostate cancer at MSK, the researchers identified 2907 patients who were managed with active surveillance from 2000 to 2017. The study was then focused on a subgroup of 2664 patients who had Grade Group 1 disease (Gleason score ≤6).
As part of the active surveillance approach used for the patients, the treating physicians at MSK had recommended confirmatory biopsy. Patient status was reexamined every 6 months with a review of symptoms, a PSA test, and a digital rectal examination (DRE). In more recent years, MRI was increasingly used at these follow-up visits. Repeat biopsy was done every 2 to 3 years, or following changes in MRI/DRE or a sustained increase in PSA level.
The median patient age was 62 years (range, 57-68), the median PSA at diagnosis was 5 ng/ml, the median number of positive cores at diagnosis was 1, the median total cores at diagnosis was 12, and the median nomogram risk of locally advanced disease was 35. The clinical stages at diagnosis were T1C or less (89%), T2A (9.3%), T2B (1.3%), T2C (0.9%).
The treatment-free probability was 76% (95% CI, 74-78), 64% (95% CI, 61-68) and 58% (95% CI, 51-64), at 5, 10, and 15 years, respectively. The number of men at risk for metastasis was 1146, 220, and 25 at those same 3 cutoff points, respectively.
Beyond the 10-year risk of distant metastasis of 0.6%, the risk of distant metastasis was 1.5% (95% CI, 0.4-5.2) at 15 years.
“While these rates align with those of other active surveillance cohorts and support the oncologic safety of active surveillance over longer term follow-up, we do note that the upper bound of the confidence interval at 15 years is clinically relevant (5.2% risk of metastasis). However, of the 5 patients with distant metastases, only 2 might have been cured by early treatment.”
The overall survival rate at 10 years was 94% (95% CI, 92-95). Among the 2664 men with Grade Group 1 prostate cancer, only 1 died of prostate cancer.
“Our experience confirms, on a large scale, prior reports that active surveillance is an oncologically safe strategy for men diagnosed with low risk prostate cancer. Active surveillance should be strongly recommended for such patients as it avoids treatment related morbidity without compromising cancer control,” Carlsson et al concluded.
Carlsson S, Benfante N, Alvim R, et al. Long-term outcomes of active surveillance for prostate cancer: The Memorial Sloan Kettering Cancer Center experience. J Urol. 2020;203:1122-1127. https://doi.org/10.1097/JU.0000000000000713