Anal Cancer Study Based on Korea Central Cancer Registry Data: One Step Forward in Clinical Research
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First of all, I would like to congratulate the authors of this work, which focused especially on rare tumors and anal cancer based on National Cancer Registry data. For colorectal surgeons, knowledge of oncologic outcomes for anal cancer is important for making a therapeutic decision. Furthermore, these outcomes should be based on Korean Cancer Registry data. Anal cancer constitutes a relatively small portion of gastrointestinal tract cancers [1]. However, anal cancers are probably underreported because some anal canal tumors are misclassified as rectal tumors. Wide geographical and racial variations in the incidence of cancers are observed around the world. The incidence and the survival rates are generally well publicized for the more common cancers, such as lung, breast, and colorectal tumors; however, little is written regarding the incidence and the survival rates for anal canal cancer. Although some authors have reported clinicopathologic features or prognostic factors for anal cancers [2, 3], the characteristics of and the survival rate for anal cancer in Korea are largely unknown because no population-based study has been performed to address these issues in Korea.
For decades, in many countries and regions, registration of cancers has been mandatory. National cancer registration is rooted in public health, helps in the planning of health services, and can be an important tool in clinical research. However, sometimes clinicians are frustrated because the cancer registry cannot provide all the information they need. A limitation in this study based on Korea Central Cancer Registry data is that the database lacks information on interventions such as surgery, radiation, and chemotherapy, on time to any type of recurrence, or on aspects of quality of care for anal canal cancer.
The authors compared the survival between males and females by Surveillance, Epidemiology and End Results (SEER) stage and found that survival rates showed a diffference according to sex and age which was related to the distinct features of Korean patients with anal cancer [4]. This study is the largest to date that reports population-based survival data for anal canal cancer in Korea, and it provides an updated picture of anal canal cancer during the past 17 years. Even though the results could be representative of the population in Korea and should be more meaningful than single-institution experiences, this study has some limitations. The study did not analyze oncologic oucomes according to TNM stage, therapeutic modality, or recurrence pattern.
In the future, the detailed parameters must be checked before analyzing Korean Cancer Registry database. Additionally, current data needs to be compared with published single-institution anal cancer data. Finally, prospective multicenter studies based using clinical databases on rare cancers need to be done to improve the quality of the data.