Tumour grade, treatment, and relative survival in a population-based cohort of men with potentially curable prostate cancer

Abstract

Background: There is insufficient information regarding the benefit of treatment with curative intent for men with localised poorly differentiated prostate cancer (PCa).

Objective: To evaluate relative survival in men with potentially curable PCa in relation to Gleason score (GS) and treatment as practiced in the community at large.

Design, setting, and participants: A population-based study including all men with localised PCa registered in Sweden's National Prostate Cancer Register.

Interventions: Hormonal therapy, watchful waiting, and treatment with curative intent.

Measurements: The ratio of observed deaths to expected deaths, determined from survival in the general male population of the same age, was assessed using Poisson regression analysis, with GS and treatment as covariates. Interaction between GS and treatment was tested in a multivariate Cox proportional hazard analysis.

Results and limitations: A total of 31,903 men with potentially curable tumour (T1-T3, N0/NX, M0/MX, age <75 yr, and prostate-specific antigen [PSA] <20 ng/ml) were identified. GS was recorded for 28,454 of these men. Some 19,606 men (60.8%) were treated with curative intent, and 12,645 men (39.2%) were given either hormonal treatment or expectant management. The ratios between observed and expected survival gradually increased for men with GS 10, with GS to 3.3 for men treated conservatively and to 1.4 for men treated with curative intent. There was a significant interaction between GS and treatment, with a relatively greater benefit from treatment with curative intent for men with high-grade tumours. The results have to be interpreted with some caution, as there was no randomisation between the treatment groups.

Conclusions: Survival for men with well-differentiated tumours is close to that of the general population, regardless of treatment, but the outcome is dismal for men with poorly differentiated tumours, whichever treatment is applied. Nevertheless, men with poorly differentiated tumours benefit more from curative treatment than do men with well- differentiated tumours.