Surveillance: Reclassification risk drops after 2 years

Baltimore-New findings from the Johns Hopkins University School of Medicine in Baltimore should be useful to clinicians looking to counsel anxious prostate cancer patients who are undergoing active surveillance. 

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Analyses of data from the prospectively maintained Johns Hopkins Active Surveillance Study show that reclassification rates are not equally distributed across time or risk groups, researchers reported at the 2015 AUA annual meeting in New Orleans.

Their study, which was subsequently published in the Journal of Urology (2015; 193:1950-5), included data from 808 men enrolled since January 2005 who were compliant with all follow-up biopsies, of whom 557 were categorized as very low risk and 251 were low risk. Kaplan-Meier survival analysis with adjustments for covariates using a Cox proportional hazards model was done to estimate freedom from reclassification.

Reclassification risk highest 2 years post-Dx

The results showed the risk of reclassification, defined as either increase in grade or volume, was highest in the first 2 years after diagnosis and was similar comparing the very low-risk and low-risk subgroups. Thereafter, the risk of reclassification by grade or volume was significantly higher in the low-risk men than in the very-low-risk subgroup (2.4-fold and 1.8-fold, respectively). In both cohorts, however, the lifetime risk declined exponentially, falling by 30% with each favorable biopsy in the low-risk subgroup and by 35% in the very-low-risk men.

Next: Findings "allow clinicians to provide patients with confident answers and to reassure men"

“Even as their follow-up in active surveillance lengthens, men continue to be concerned about whether their next biopsy will show evidence of disease progression and if they may have lost the opportunity for cure due to earlier sampling error,” said senior author Mufaddal Mamawala, MBBS, MPH, biostatistician for the Johns Hopkins Active Surveillance Study.

“The findings in our study allow clinicians to provide patients with confident answers and to reassure men who are compliant in active surveillance that their lifetime risk for reclassification falls with each non-reclassifying biopsy.”

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Dr. Mamawala told Urology Times that a model of risk using the study results indicates that the lifetime risk of reclassification falls to virtually 0 after men have undergone 10 to 12 non-reclassifying biopsies.

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Presenting the research, Ridwan Alam stated that in addition to helping inform men about their reclassification risk, the findings might lead to a shift in the monitoring protocol for men in active surveillance with an increased interval between biopsies for men at lowest risk.

“We hope that in the future, the risk of reclassification may be incorporated with other factors into a risk calculator that can be used to determine how often men in active surveillance need to undergo biopsy,” said Alam, a medical student at Johns Hopkins.

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Men in the Johns Hopkins active surveillance program are classified as very low risk if they meet all Epstein criteria. If they do not meet at least one of the Epstein criteria but meet all of the D’Amico criteria and have a Gleason score of 6, they are considered low risk.

Next: Misclassification, not progression

Misclassification, not progression

The authors suggested that the high rates of reclassification during the first 2 years of active surveillance and the lack of difference in rates between the two study subgroups likely reflects initial misclassification of disease rather than progression.

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“These men in active surveillance who are classified as very low risk or low risk all have Gleason 6 disease, and we know from previous research that true Gleason 6 prostate cancer is not likely to progress,” Alam said. “Therefore, it is likely that the ‘reclassification’ in these men is the result of picking up tumor that was missed earlier because of undersampling.”

Speaking during the discussion, co-author H. Ballentine Carter, MD, professor of urology and oncology at Johns Hopkins, noted that with the advent of magnetic resonance imaging and the ability to visualize anterior tumors, the rate of initial misclassification is expected to decline.

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