Epidemiology of Mucinous Adenocarcinomas

Abstract

Mucinous (colloid) adenocarcinomas (MAs) are a rare histological subtype of adenocarcinomas where extracellular mucin comprises more than 50% of the tumor. Most literature on MAs relate to cancers from colorectal and breast sites; however, the literature lacks a standardized overview of the MA disease entity. Particularly in colorectal cancer, some MAs may have signet ring cells floating within the mucin, which may represent a highly metastatic phenotype. MAs and signet ring cell adenocarcinomas represent a spectrum of mucin-producing neoplastic conditions where in the latter most mucin is intracellular rather than extracellular. We recently published a standardized overview of signet ring cells, and in this companion work, using a retrospective cohort approach, we summarize the clinicodemographic and mortality outcomes of MAs in sixteen primary sites, comprising 95.6% of all MAs in the Surveillance, Epidemiology, and End Results Program (SEER), a population-level cancer database covering nearly one-third of the United States population. Compared to matching nonvariant adenocarcinomas, MAs have a slightly earlier age of onset with increased rates of regional and distant disease at presentation. Survival outcomes are highly dependent on tumor location, illustrating our poor understanding of MA tumor biology. The clinical significance of MA histology depends largely on tumor site.

Keywords: cancer; chemotherapy; colloid carcinoma; histopathology; radiotherapy; surgery.

Figure 1

(a) Representative histological slide of colorectal adenocarcinoma. (b) Representative histological slide of colorectal mucinous adenocarcinoma, illustrating abundant extracellular mucin within more than 50% of the tumor area. Figures sourced from Wikimedia Commons, public domain [8,9].

Figure 2

(a) Distribution of mucinous adenocarcinomas in Surveillance, Epidemiology, and End Results Program (SEER), 1975–2016, total of 169,595 cases. (b) Distribution of all solid (non-blood borne), non-mucinous tumors in SEER, 1975–2016, total of 9.44 million cases. In both plots data labels are percentages. Markers omitted if less than 1%.

Figure 3

Kaplan–Meier survival curves. All survivor functions are shown with 95% confidence intervals. (a) Colon cancer. (b) Breast cancer. (c) Lung cancer. (d) Rectal cancer. (e) Pancreatic cancer. (f) Gastric cancer. (g) Appendiceal cancer. (h) Gallbladder/Biliary cancer. (i) Small Bowel cancer. (j) Prostate cancer. (k) Prostate cancer. (l) Urinary Bladder cancer. (m) Anal cancer. In these curves, “All” represents the curves for all cancers within that site, with subtypes shown as labelled. Among subtypes, pairwise statistical comparisons by the log-rank test is shown relative to mucinous adenocarcinomas.

Figure 3

Kaplan–Meier survival curves. All survivor functions are shown with 95% confidence intervals. (a) Colon cancer. (b) Breast cancer. (c) Lung cancer. (d) Rectal cancer. (e) Pancreatic cancer. (f) Gastric cancer. (g) Appendiceal cancer. (h) Gallbladder/Biliary cancer. (i) Small Bowel cancer. (j) Prostate cancer. (k) Prostate cancer. (l) Urinary Bladder cancer. (m) Anal cancer. In these curves, “All” represents the curves for all cancers within that site, with subtypes shown as labelled. Among subtypes, pairwise statistical comparisons by the log-rank test is shown relative to mucinous adenocarcinomas.

Figure 3

Kaplan–Meier survival curves. All survivor functions are shown with 95% confidence intervals. (a) Colon cancer. (b) Breast cancer. (c) Lung cancer. (d) Rectal cancer. (e) Pancreatic cancer. (f) Gastric cancer. (g) Appendiceal cancer. (h) Gallbladder/Biliary cancer. (i) Small Bowel cancer. (j) Prostate cancer. (k) Prostate cancer. (l) Urinary Bladder cancer. (m) Anal cancer. In these curves, “All” represents the curves for all cancers within that site, with subtypes shown as labelled. Among subtypes, pairwise statistical comparisons by the log-rank test is shown relative to mucinous adenocarcinomas.