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Anal Canal Carcinoma

Anal Canal Carcinoma Deep Research Fallback

⚠️ Fallback MONDO:0007108

Anal Canal Carcinoma Deep Research Fallback

Provider Attempts

  • 2026-05-13T00:00Z: just research-disorder asta Anal_Canal_Carcinoma failed: agentapi not found in PATH and no provider API keys configured (OPENAI_API_KEY, EDISON_API_KEY, ASTA_API_KEY, PERPLEXITY_API_KEY all unset in this environment).
  • 2026-05-13T00:00Z: just research-disorder openai Anal_Canal_Carcinoma failed for the same reason.
  • 2026-05-13T00:00Z: just research-disorder perplexity Anal_Canal_Carcinoma failed for the same reason.
  • 2026-05-13T00:00Z: just research-disorder falcon Anal_Canal_Carcinoma failed for the same reason.

No provider-generated research artifact was available to integrate. Curation therefore proceeded from previously fetched PubMed abstracts in references_cache/, without hand-editing any cache files.

Literature Synthesis

The following PMIDs were used to anchor the curated kb/disorders/Anal_Canal_Carcinoma.yaml entry. Each citation below corresponds to the cached abstract in references_cache/PMID_<id>.md and is attributed to the role it plays in the pathophysiology/clinical model.

HPV etiology and viral mechanism

  • PMID:42101137 (J Med Virol 2026) — "Causative Human Papillomavirus (HPV) Genotypes of Anal Cancers in Australian Cisgender Women." Laser-capture microdissection of anal SCC lesions attributed HPV-16 as the causal genotype in the great majority of cases (93.3% HPV16). Anchors the HPV-16-dominant etiology, the infectious_agent and environmental entries for HPV, the HPV vaccination prevention rationale, and the higher risk of anal cancer in MSM living with HIV.
  • PMID:2175676 (Cell 1990) — "The E6 oncoprotein encoded by human papillomavirus types 16 and 18 promotes the degradation of p53." Classic biochemical study showing that the E6 proteins of oncogenic HPV types stimulate ATP- and ubiquitin-proteasome-dependent degradation of p53. Anchors the E6 Oncoprotein-Mediated p53 Degradation pathophysiology node and the upstream half of the HPV → p53 loss → genomic instability axis.
  • PMID:2537532 (Science 1989) — "The human papilloma virus-16 E7 oncoprotein is able to bind to the retinoblastoma gene product." Founding biochemical evidence that HPV-16 E7 binds and inactivates pRB. Anchors the E7 Oncoprotein-Mediated pRB Inactivation pathophysiology node and the upstream half of the E7 → pRB inactivation → uncontrolled S-phase entry axis.

Risk factors and natural history

  • PMID:15241823 (Cancer 2004) — "Human papillomavirus, smoking, and sexual practices in the etiology of anal cancer." Population-based case-control study identifying current cigarette smoking as an independent risk factor for anal cancer in both men and women, independent of HPV-related sexual exposures. Anchors the tobacco-smoking entry under environmental.
  • PMID:40019005 (J Low Genit Tract Dis 2025) — "Recent Guidelines on Anal Cancer Screening: A Systematic Review." Systematic review of society screening guidelines describing the AIN-to-invasive-SCC progression pathway, the role of high-resolution anoscopy in high-risk groups, and the benefit of treating precancerous anal lesions. Anchors the Anal Intraepithelial Neoplasia Progression pathophysiology node and the high-resolution anoscopy diagnostic entry.

Molecular and immune profiling

  • PMID:34790403 (J Gastrointest Oncol 2021) — "Molecular characterization of squamous cell carcinoma of the anal canal." Multiplatform molecular profiling of 311 anal SCC specimens reporting recurrent somatic mutations in PIK3CA (28.1%), KMT2D (19.5%), FBXW7 (12%), TP53 (12%), and PTEN (10.8%), as well as PD-L1 expression in 40.5% of tumors and PD-1 expression on infiltrating cells in 68.8%. Anchors the Genomic Instability and Adaptive Immune Resistance pathophysiology nodes, the TP53 and PIK3CA genetic entries, the histopathology entry for anal SCC, and the rationale for PD-1 checkpoint blockade.

Clinical presentation and regional spread

  • PMID:33085290 ("Rectal Bleeding.") — Reference clinical definition of hematochezia as the passage of frank blood per rectum. Anchors the Rectal Bleeding (Hematochezia) phenotype entry as the most common presenting symptom of anal canal cancer.
  • PMID:37731305 (Ann Palliat Med 2023) — "Palliative care in colorectal and anal malignancies from diagnosis to death." Palliative care review of colorectal and anal malignancies documenting pain among the multiple symptoms commonly experienced by patients with these cancers. Anchors the Anal Pain phenotype entry; the description was deliberately scoped to the palliative-care evidence base (see Round-2 review fix).
  • PMID:39882228 (J Anus Rectum Colon 2025) — "Metastatic Status and Dissection Effect of Regional/Extraregional Lymph Nodes in Japanese Patients with Squamous Cell Carcinoma of the Anal Canal." Multicenter retrospective cohort of 435 anal canal SCC patients documenting that primary tumor progression is associated with inguinal lymph node metastasis and recurrence. Anchors the Inguinal Lymphadenopathy phenotype entry and the lymphatic drainage pattern of the anal canal below the dentate line.

Epidemiology, histology, and treatment

  • PMID:41452529 (Int J Clin Oncol 2026) — "Cancer epidemiology in rare and hereditary colorectal diseases 2) anal canal cancer (cancer statistics)." Japanese and Western registry data documenting that anal canal cancer histology varies by population (Japan: 66.8–75.5% adenocarcinoma, 16.2–24.4% SCC; Western: 70–85% SCC), that HPV-16 is the most prevalent genotype in HPV-positive SCC (85% HPV-positive), and that adoption of chemoradiotherapy rose from 14% in the 1990s to >80% after
  • Anchors the SCC and adenocarcinoma subtype/histopathology entries, the HPV infection pathophysiology node, the histopathology diagnostic entry, and the Nigro-regimen chemoradiation treatment entry.
  • PMID:15571466 (Expert Opin Pharmacother 2004) — "Chemotherapeutic options in the management of anal cancer." Review establishing that, since Nigro's original 1974 contribution, the chemotherapy backbone for anal cancer has remained 5-fluorouracil plus mitomycin C, given concurrently with radiation. Anchors the Chemoradiation (Nigro regimen) treatment entry and the use of 5-FU and mitomycin C as therapeutic_agent values.
  • PMID:37210274 (Eur J Surg Oncol 2023) — "Survival outcomes following salvage abdominoperineal resection for recurrent and persistent anal squamous cell carcinoma." Multicenter retrospective cohort establishing salvage abdominoperineal resection as the primary treatment for locoregional failure after chemoradiation for anal SCC. Anchors the Salvage Abdominoperineal Resection treatment entry.
  • PMID:35114169 (Lancet Gastroenterol Hepatol 2022) — "Pembrolizumab for previously treated advanced anal squamous cell carcinoma: results from the non-randomised, multicohort, multicentre, phase 2 KEYNOTE-158 study." Phase 2 KEYNOTE-158 anal SCC cohort supporting pembrolizumab as an active second-line treatment for advanced anal SCC. Anchors the Immune Checkpoint Inhibitor Therapy treatment entry and the target_mechanisms link from PD-1 blockade to the Adaptive Immune Resistance pathophysiology node (immune_checkpoint_blockade module conformance).

Curation Conclusions

The accepted disease model for HPV-associated anal canal carcinoma is a multi-step transformation in which:

  1. Persistent infection of basal stratified squamous epithelial cells of the anal canal (predominantly at the transformation zone) with high-risk HPV (most commonly HPV-16) establishes sustained expression of the viral oncoproteins E6 and E7.
  2. E6 targets p53 for ubiquitin-proteasome-dependent degradation (PMID:2175676), abolishing DNA damage checkpoints and apoptotic responses.
  3. E7 binds and inactivates pRB (PMID:2537532), releasing E2F transcription factors and driving uncontrolled G1/S transition and proliferation.
  4. Combined p53 and pRB inactivation, together with HPV-associated chromosomal aberrations, produces genomic instability and accumulation of driver mutations (PIK3CA, KMT2D, FBXW7, TP53, PTEN; PMID:34790403).
  5. HPV-driven dysplasia of the anal squamous epithelium progresses through AIN1 → AIN2 → AIN3/HSIL → invasive squamous cell carcinoma (PMID:40019005).
  6. Invasive anal SCC frequently upregulates PD-L1 and engages adaptive immune resistance (PMID:34790403), providing the therapeutic rationale for PD-1 blockade (PMID:35114169).

Clinically, anal canal carcinoma presents most commonly with hematochezia (PMID:33085290), anal pain (PMID:37731305), and inguinal lymphadenopathy in regional spread (PMID:39882228). HIV infection (especially in MSM) and tobacco smoking are major risk modifiers (PMID:42101137, PMID:15241823). Standard curative treatment for localized disease is the Nigro regimen of concurrent 5-FU/mitomycin-C chemoradiation (PMID:15571466, PMID:41452529), with salvage abdominoperineal resection reserved for locoregional failure (PMID:37210274), and PD-1 inhibitors (pembrolizumab, nivolumab) for recurrent or metastatic disease (PMID:35114169).

Subtypes

Curated subtypes in the YAML:

  • Anal Canal Squamous Cell Carcinoma (NCIT:C7469) — dominant histology in Western series, strongly HPV-16-driven (PMID:42101137).
  • Anal Canal Adenocarcinoma (NCIT:C7471) — rare in Western series, but more common than SCC in Japanese registries (PMID:41452529); not HPV-associated; treated more like rectal adenocarcinoma.

Items Intentionally Skipped

  • KMT2D, FBXW7, and PTEN are cited in the Genomic Instability pathophysiology node via PMID:34790403 but are not yet broken out as individual genetic entries. A follow-up curation pass can split these into per-gene entries (with the same snippet as the parent entry) if schema-level gene-level granularity is desired.
  • The Nigro regimen treatment_term currently uses MAXO:0000014 (radiation therapy) with 5-FU and mitomycin C as therapeutic_agent values. NCIT:C94626 (Chemoradiotherapy) would better represent the combined-modality nature of the regimen; this is a follow-up refinement flagged in Round-3 review.