LOS ANGELES – Primary small cell cancer of the anus is a rare but devastating condition and overall survival may not be improved with surgical treatment.
Those are key findings from what is believed to be the largest analysis of its kind to date.
“There are very limited data for patients with anal small cell cancers who need preoperative counseling and risk stratification,” study author Dr. Cornelius A. Thiels said in an interview at the annual meeting of the American Society of Colon and Rectal Surgeons. “There are also no data to guide treatment, so, until now, management was based on the treatment of small cell of the lung, and other anal cancers.”
Cancers of the anal canal are estimated to represent about 2.5% of all gastrointestinal neoplasms, while primary small cell cancer of the anus is believed to account for less than 1% of all anal neoplasms, according to Dr. Thiels, who is a third-year general surgery resident in the department of surgery and a surgical outcomes fellow in the Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery at the Mayo Clinic, Rochester, Minn.
In an effort to evaluate the outcomes of patients with primary small cell cancer of the anus, the researchers reviewed their own institutional experience in treating nine patients with this condition between from 1994-2014, as well as National Cancer Data Base (NCDB) records of 174 patients from 1998-2014. The NCDB is maintained by collecting data prospectively from more than 1,500 facilities across the United States and is estimated to capture approximately 70% of all newly diagnosed cases of cancer annually. Institutional data allowed the researchers to identify details, including how these patients presented and what type of chemotherapy they received. However, analysis of a national database was necessary given the rarity of the diagnosis.
In the analysis of NCDB records, the mean patient age was 59 years and 74% were female. Most of the tumors (95%) were high grade and the majority of patients presented with advanced disease (50 with stage IV disease, 49 with stage III disease, 29 with stage II disease, 25 with stage I disease, and 21 with unknown stage). Overall survival was 66% at 12 months and 29% at 36 months. Among patients with stage I-III disease, survival was 72% at 12 months and 39% at 36 months.
Of the 103 patients with stage I-III disease, 95% received medical therapy, 70% underwent medical management alone, while 30% underwent surgery with curative intent. Patients who did not undergo surgery tended to have a higher stage of disease, compared with those who did (57% vs. 26%: P = .005). Overall survival at 36 months was similar between the two groups (33.9% in the surgery group vs. 35.8% in the no surgery group; P = .87).
“Unfortunately, it seems from our own experience and from national data that additional research is needed to determine how best to treat these patients and that surgery may not prolong survival in many of these patients,” Dr. Thiels said. “Although additional research is needed to optimize outcomes for these patients, harnessing the power of a national cancer database like the NCDB allows us to improve our understanding of these otherwise extremely rare, and difficult to study, tumors.”
Dr. Thiels reported having no financial disclosures.