Population–Based Evaluation of Adenosquamous Carcinoma of the Colon and Rectum

Abstract

Background Information about adenosquamous carcinoma of the colon and rectum is scarce due to its extremely low incidence. Objective To examine the prognostic significance of a histological diagnosis of adenosquamous carcinoma compared to adenocarcinoma of the colon and rectum. Design Retrospective study. Setting California Cancer Regisry data from 1994 through 2004 with follow up through 2008. Patients Surgically treated cases of cancer of the colon and rectum excluding anus with tumor histology of adenocarcinoma and adenosquamous carcinoma. Main outcome measures Histology-specific survival analyses (using Kaplan-Meier method), and overall and colorectal-specific mortality (using multivariable Cox proportional hazards regression analyses). Results A total of 111,263 adenocarcinoma and adenosquamous carcinoma of colon and rectal cancer cases were identified (adenocarcinoma 99.91%, and adenosquamous carcinoma: 0.09%). There was no significant difference in sex, age, race and socioeconomic status between two groups. The most common location of adenocarcinoma and adenosquamous carcinoma was the right colon and transverse colon. The adenosquamous carcinoma group was significantly associated with higher rate of metastasis at the time of operation (adenosquamous carcinoma: 36.56% vs. adenocarcinoma: 13.92%) and with poorly differentiated tumor grade (adenosquamous carcinoma: 65.96% vs. adenocarcinoma: 19.74%) compared to the adenocarcinoma group. The median overall survival time was significantly greater in the adenocarcinoma group (82.4 months) compared with the adenosquamous carcinoma group (35.3 months). Using multivariable hazard regression analyses, adenosquamous carcinoma histology was independently associated with increased overall mortality (Hazard Ratio: 1.67) and colorectal-specific mortality (Hazard Ratio: 1.69) compared with adenocarcinoma. Conclusions This is one of the largest studies of adenosquamous carcinoma of the colon and rectum to date. This uncommon colorectal cancer subtype was associated with higher overall and colorectal-specific mortality compared with adenocarcinoma. Among colorectal cancer cases, adenosquamous carcinoma histology should be considered a poor prognostic features.

Adenosquamous Carcinoma of the Cecum: A Rare but Aggressive Form of Colonic Neoplasia

“…These findings were reported in a case series involving 44 patients in whom the youngest patient was 19 years old at the time of diagnosis [7]. Other studies reported a mean age of 65 to 67 years at the time of diagnosis [2][3]. In a study by Masoomi et al, a higher proportion of colorectal ASC cases, when compared to cases of colon adenocarcinoma, presented before the age of 60 (37% versus 22%) [2,10].…”

“…Early studies suggested that the sigmoid colon and rectum are the most common sites of primary colorectal ASC [3]. However, a number of more recent studies have shown the distribution of colorectal ASC to be similar to that of colorectal adenocarcinoma with the right side of the colon being more commonly affected [2,7]. Due to the rarity of the disease, no specific pattern of patient presentation or predictors of clinical outcomes have been identified to date.…”

“…In a study by Masoomi et al, a higher proportion of colorectal ASC cases, when compared to cases of colon adenocarcinoma, presented before the age of 60 (37% versus 22%) [2,10]. Based on these reports, it appears that ASC of the colon occurs at a younger age compared to colon adenocarcinoma.ASC of the colon affects males and females equally [2][3]7] and 70% to 84% of cases involve Caucasians [2][3]. Early studies suggested that the sigmoid colon and rectum are the most common sites of primary colorectal ASC [3].…”

“…Due to the rarity of the disease, no specific pattern of patient presentation or predictors of clinical outcomes have been identified to date. A few cases of ASC of the colon have been found in the setting of hypercalcemia, which is thought to be a paraneoplastic phenomenon [2,11,12]. It has been proposed that the squamous cell component of colorectal ASC results in an increased potential for metastasis, thus leading to a worse prognosis [6].…”

“…Based on recent studies, ASC constitutes 0.06 to 0.09% of all colorectal cancers [2,3]. The most common cause of squamous histopathology in a colonic mass is a metastatic lesion, which has to be ruled out before it is deemed to be of colonic origin.…”