Commentary on "Characteristics and Survival of Korean Anal Cancer From the Korea Central Cancer Registry Data"

To the editor:

I read with great interest Park et al. [1]'s study, which is one the largest reports on anal canal cancer published in the literature. It provides valuable information regarding the characteristics of and the outcomes for Korean patients with anal canal cancer. The study has mainly focused on the prognostic impact of age, sex, stage, and study duration on the 5 year relative overall survival rates. However, as declared by the authors, due to the limitations of their database, the study lacks important clinical data. Kim [2] well pointed out some of the study's limitations in the editorial entitled, "Anal Cancer Study Based on Korea Central Cancer Registry Data: One Step Forward in Clinical Research". Park et al. [1]'s study did not address a mean or a median age for the entire study population. Malignant neoplasms of the anal canal tend to present in the sixth and the seventh decades of life and rarely before the second decade [3]. The distributions of tumor characteristics such as histologic type, stage and tumor grade between themselves and among different sex and age groups have not been provided. In addition, the modalities used to treat different stages and histological types were not addressed. The treatment approach is usually based on histological type, disease stage, and patient's performance status and desire [3, 4]. Finally, the authors did not compare the patients' and the tumor's characteristics and the 5 year overall survival rates in their study to those previously reported in the literature for large series [5, 6]. Herein, we provided a table (Table 1) to present and compare the patients demographics, the histological types and the 5 year overall survival rates in Park et al. [1]'s study and in two of the largest reports of anal canal cancer from Australia and the United States [1, 5, 6]. Accordingly, the female/male ratio of Korean patients with anal canal cancer is comparable to the values reported in the literature [3, 5, 6]. Park et al. [1] found a lower (50% vs 70% and 77%) proportion for squamous cell carcinomas and a higher (32% vs 27.5% and 19%) one for adenocarcinomas, which is different from most reported series. Furthermore, the average 5-year-survival of Korean patients with anal canal cancer is consistent with the values for most reported series [3, 5, 6].

Table 1

Patient characteristics, clinicopathologic features and overall survival for patients with anal canal cancer based on the three largest reported series in the literature