The benefit of PSA screening for early detection of prostate cancer is controversial. A recent study used two models to examine the future impact of the change of mind in the guidelines (in favor of not screening).
(ag) The risk of overdiagnosis of prostate cancer with PSA screening is well known. Especially in older men, this study should be interpreted with caution. Studies also showed that screening saves few lives, provided that screened men are followed up for a sufficiently long period (11-13 years). Therefore, new clinical guidelines recommend avoiding routine PSA testing altogether or at least in men older than 70 years. What impact could this change of direction have in the future? A new study explored this question.
Projection to 2025
The authors hypothesized a survival benefit of PSA screening, consistent with previous study results. Using two models of the natural history and future diagnosis of prostate cancer, they calculated the effect of continuing PSA screening versus not doing so.
The models were based, among other things, on incidence figures of prostate cancer from the USA. This predicted incidence on the one hand and mortality on the other hand between the years 2013 and 2025 with or without screening. The study population included both men older than 70 years and younger.
Waiver could have negative consequences
The models predict that continued screening (applied at the same frequency as before and to all men) would generate 710,000 (up to 1,120,000 depending on the model) overdiagnoses but would also prevent 36,000-57,000 cancer deaths over the entire period.
Eliminating PSA testing in all men eliminates 100% of all future overdiagnoses, but at the same time misses 100% of preventable deaths, according to the models.
If screening is performed only in men under 70 years of age, approximately 64-66% of the aforementioned overdiagnoses can be eliminated, and deaths can also be prevented more frequently (although not always: 36-39% of these will still occur with scree-ning).
Younger patients benefit
The authors conclude that not screening all men could result in adverse outcomes. This would result in many preventable deaths. Continued screening of men younger than 70 years could prevent more than half of preventable deaths. This with significantly reduced rates of overdiagnosis compared to screening in patients of all ages. Thus, a general waiver in favor of a reasonable age cap would have to be reconsidered.
Source: Gulati R, et al: Expected population impacts of discontinued prostate-specific antigen screening. Cancer 2014. doi: 10.1002/cncr.28932.
InFo Oncology & Hematology 2014; 2(7): 3.
