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Adenoma-like adenocarcinoma is a form of bowel cancer whose invasive part still looks like a harmless polyp under the microscope, which is why it is often reported as an adenoma on biopsy and only recognised once the bowel is removed. Despite frequently growing deep into the bowel wall, it spreads to lymph nodes less often than ordinary bowel cancer and does better.
What it is. The fifth edition of the World Health Organization classification of digestive tumours added adenoma-like adenocarcinoma as a subtype of colorectal adenocarcinoma (Nagtegaal 2020). The invasive component keeps the low-grade villous or tubulovillous architecture and cytology of an adenoma, with pushing rather than infiltrative invasion and little or no desmoplastic stroma, so material taken at endoscopy does not look malignant.
How it differs from its parent. In a series of 35 such carcinomas, 43 percent had been reported as an adenoma on the preceding biopsy and 60 percent of the resections showed no residual conventional adenoma; despite an advanced T category in 66 percent, only 20 percent had nodal metastases and 15 percent developed distant metastases, and KRAS mutation was frequent (Histopathology 2016). A later review of resected stage I to III colonic adenocarcinomas from one institution classified 91 as adenoma-like, 71 percent of them purely so, and compared them with 251 adenocarcinomas of no special type (Hum Pathol 2021).
How common it is. Ninety-one tumours against 251 of no special type in the single-institution series above, which is the only published frequency. Because the diagnosis rests on recognising the pattern, it depends on the pathologist and on whether a partial component counts; no national registry records it.
How it is treated. No trial has been run in this histology. Treated as colorectal adenocarcinoma: resection with adjuvant chemotherapy by stage when removable, the systemic rows of the parent page when not; the parent record carries the trials. The clinically important point is diagnostic rather than therapeutic: a biopsy reported as adenoma in a patient whose scan or endoscopy shows a mass should not close the question, and the possibility of this subtype is the reason why.
In one American series of resected stage I to III colonic adenocarcinomas from 2013 to 2016, 91 tumours were classified as adenoma-like against 251 of no special type, and 71 percent of the adenoma-like tumours were composed entirely of adenoma-like tissue. No registry count is published.
Right-sided tumours behave differently from left-sided and rectal ones; the colon drains along its mesenteric vessels, the rectum into the mesorectum and pelvic side wall.
Same organ: Colon cancer (adenocarcinoma of the colon), Micropapillary adenocarcinoma of the colon and rectum, Lynch syndrome-associated colorectal cancer, Familial adenomatous polyposis-associated colorectal cancer, Mucinous adenocarcinoma of the colon and rectum, Signet ring cell carcinoma of the colon and rectum, Medullary carcinoma of the colon, Serrated adenocarcinoma of the colon and rectum, Peritoneal mesothelioma, Colorectal cancer, Rectal cancer, Mismatch-repair deficient (MSI-high) colorectal cancer, BRAF V600E-mutant colorectal cancer, HER2-amplified colorectal cancer, KRAS G12C-mutant colorectal cancer, Early-onset colorectal cancer (under 50), Anal cancer (squamous cell carcinoma), Appendiceal cancer and pseudomyxoma peritonei, Small intestine cancer (small bowel adenocarcinoma), Small intestinal neuroendocrine tumours, Anal high-grade squamous intraepithelial lesions (precursor), Localised anal squamous cell carcinoma (stage I to III), Metastatic and recurrent anal squamous cell carcinoma, Low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei, Appendiceal adenocarcinoma (mucinous and non-mucinous, including signet ring cell), Goblet cell adenocarcinoma of the appendix, Localised small bowel adenocarcinoma (stage I to III, resected), Advanced and metastatic small bowel adenocarcinoma
Resection with adjuvant chemotherapy decided by stage as for colorectal adenocarcinoma of no special type; the deceptive biopsy appearance means the diagnosis is often made only on the resection specimen.
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Query for this cancer: (TITLE:"Adenoma-like adenocarcinoma of the colon and rectum" OR ABSTRACT:"Adenoma-like adenocarcinoma of the colon and rectum" OR TITLE:"Adenoma-like adenocarcinoma of the colon and rectum invasive cancer that looks like an adenoma on biopsy; better outlook" OR ABSTRACT:"Adenoma-like adenocarcinoma of the colon and rectum invasive cancer that looks like an adenoma on biopsy; better outlook" OR TITLE:"Adenoma-like colorectal adenocarcinoma" OR ABSTRACT:"Adenoma-like colorectal adenocarcinoma" OR TITLE:"Villous adenoma-like adenocarcinoma" OR ABSTRACT:"Villous adenoma-like adenocarcinoma" OR TITLE:"Invasive papillary adenocarcinoma of the colon" OR ABSTRACT:"Invasive papillary adenocarcinoma of the colon") AND (treatment OR therapy OR trial OR survival OR diagnosis). Results are unfiltered search hits about Adenoma-like adenocarcinoma of the colon and rectum, not a curated reading list.
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Bleeding that does not stop by itself, bleeding from more than one site, or new bruising in several places or one large area.
The bowel cancer regimens share low blood counts, tiredness, sickness and a sore mouth. Oxaliplatin adds cold-triggered tingling, irinotecan adds early and late diarrhoea, capecitabine adds hand-foot syndrome and needs a DPD test first, and cetuximab or panitumumab add an acne-like rash and low magnesium. The rule for all of them: ring the 24-hour number rather than wait.
See all on the product pages:CAPOX (capecitabine, oxaliplatin)FOLFOX (5-FU, leucovorin, oxaliplatin)·Printable cards in the navigator
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