Dear Editor,

With considerable interest, we read the article published by Stolzenbach et al. [1], who compared stage and cancer-specific mortality (CSM) of prostate cancer (PCa) patients with different residency status. This particular topic is an important clinical issue. As such, there are a few points that we would like to bring up.

  1. 1.

    The factors extracted by the authors from the SEER database (2004–2016) include clinical T stage and clinical N stage. However, according to the SEER Program [2], the “clinical stage” variable was not provided in the dataset until 2016. Therefore, for patients diagnosed before 2016, it was impossible for researchers to identify the clinical stage. How to obtain the clinical stage of patients diagnosed between 2004 and 2016 needs to be explained in detail.

  2. 2.

    Some of the patients included in the analysis received chemotherapy. This type of treatment should be taken into consideration since previous literature showed that chemotherapy holds great potential in the management of PCa patients [3, 4].

  3. 3.

    Their study included patients with primary PCa but did not exclude multiple primary cancers. However, a prior SEER-based study demonstrated there were at increased risk for cancers of soft tissue including heart, bladder, kidney, and endocrine system among PCa men compared with the general population, which may affect patients' survival [5].