Location Has Prognostic Impact on the Outcome of Colorectal Mucinous Adenocarcinomas

Abstract

Mucinous (colloid) adenocarcinomas (MAs) are a rare histological subtype of tumors defined by extracellular mucin comprising more than 50% of the tumor. These tumors are on a continuum of mucin-producing malignancies with signet ring cell adenocarcinomas (SRCCs), which instead produce intracellular mucin. Mucin-containing cancers occur primarily in the stomach and colon, where for SRCCs, outcomes are relatively worse in the proximal stomach and the rectum. It is not known if MAs have similar outcomes. In this study, we use the Surveillance, Epidemiology, and End Results (SEER) database to examine the effects of tumor localization, age, sex, and stage on colorectal and gastric cancer outcomes for MAs. For right colon cancers, MAs are more common, particularly in females, and have slightly better or equivalent outcomes across all stages and ages compared to conventional adenocarcinomas, but outcomes are progressively worse compared to conventional adenocarcinomas for left colon and rectal cancers. Unlike SRCCs, MAs have similar outcomes to conventional adenocarcinomas in all stomach locations. Overall, these results suggest that MAs have an intrinsically different tumor biology in the left colon and rectum that promotes pathogenesis. Decoding this phenomenon could lead to more effectively tailored patient treatment regimens.

Keywords: cancer; chemotherapy; colloid adenocarcinomas; epidemiology; histopathology; radiotherapy; signet ring cell adenocarcinomas; surgery; survival outcomes.

Figure 1

Kaplan–Meier survival curves for all stages of colorectal cancer, shown with 95% confidence intervals. (a) All locations, all ages. (b) All locations, age < 50. (c) All locations, age ≥ 50. (d) Right colon, all ages. (e) Right colon, age < 50. (f) Right colon, age ≥ 50. (g) Left colon, all ages. (h) Left colon, age < 50. (i) Left colon, age ≥ 50. (j) Rectal, all ages. (k) Rectal, age < 50. (l) Rectal, age ≥ 50. p-values between curves generated using log-rank test.

Figure 2

Kaplan–Meier survival curves for local colorectal cancer, shown with 95% confidence intervals. (a) All locations, all ages. (b) All locations, age < 50. (c) All locations, age ≥ 50. (d) Right colon, all ages. (e) Right colon, age < 50. (f) Right colon, age ≥ 50. (g) Left colon, all ages. (h) Left colon, age < 50. (i) Left colon, age ≥ 50. (j) Rectal, all ages. (k) Rectal, age < 50. (l) Rectal, age ≥ 50. p-values between curves generated using log-rank test.

Figure 3

Kaplan–Meier survival curves for regional colorectal cancer, shown with 95% confidence intervals. (a) All locations, all ages. (b) All locations, age < 50. (c) All locations, age ≥ 50. (d) Right colon, all ages. (e) Right colon, age < 50. (f) Right colon, age ≥ 50. (g) Left colon, all ages. (h) Left colon, age < 50. (i) Left colon, age ≥ 50. (j) Rectal, all ages. (k) Rectal, age < 50. (l) Rectal, age ≥ 50. p-values between curves generated using log-rank test.

Figure 4

Kaplan–Meier survival curves for distant colorectal cancer, shown with 95% confidence intervals. (a) All locations, all ages. (b) All locations, age < 50. (c) All locations, age ≥ 50. (d) Right colon, all ages. (e) Right colon, age < 50. (f) Right colon, age ≥ 50. (g) Left colon, all ages. (h) Left colon, age < 50. (i) Left colon, age ≥ 50. (j) Rectal, all ages. (k) Rectal, age < 50. (l) Rectal, age ≥ 50. p-values between curves generated using log-rank test.

Figure 5

Graphical summary of key findings. Percent distribution of each cancer histology (black, conventional adenocarcinoma; red, mucinous adenocarcinoma; blue, signet ring cell adenocarcinoma) for the right colon, left colon, and rectal region. Mortality hazard ratios compared to conventional adenocarcinomas, with 95% confidence intervals in brackets. AdenoCa, conventional adenocarcinoma; MA, mucinous adenocarcinoma; SRCC, signet ring cell adenocarcinoma; HR, hazard ratio.