Diagnostic performance of a faecal immunochemical test for patients with low-risk symptoms of colorectal cancer in primary care: an evaluation in the South West of England.

BACKGROUND: The faecal immunochemical test (FIT) was introduced to triage patients with low-risk symptoms of possible colorectal cancer in English primary care in 2017, underpinned by little primary care evidence. METHODS: All healthcare providers in the South West of England (population 4 million) participated in this evaluation. 3890 patients aged ≥50 years presenting in primary care with low-risk symptoms of colorectal cancer had a FIT from 01/06/2018 to 31/12/2018. A threshold of 10 µg Hb/g faeces defined a positive test. RESULTS: Six hundred and eighteen (15.9%) patients tested positive; 458 (74.1%) had an urgent referral to specialist lower gastrointestinal (GI) services within three months. Forty-three were diagnosed with colorectal cancer within 12 months. 3272 tested negative; 324 (9.9%) had an urgent referral within three months. Eight were diagnosed with colorectal cancer within 12 months. Positive predictive value was 7.0% (95% CI 5.1-9.3%). Negative predictive value was 99.8% (CI 99.5-99.9%). Sensitivity was 84.3% (CI 71.4-93.0%), specificity 85.0% (CI 83.8-86.1%). The area under the ROC curve was 0.92 (CI 0.86-0.96). A threshold of 37 µg Hb/g faeces would identify patients with an individual 3% risk of cancer. CONCLUSIONS: FIT performs exceptionally well to triage patients with low-risk symptoms of colorectal cancer in primary care; a higher threshold may be appropriate in the wake of the COVID-19 crisis.

Relationship between endometriosis, endometrioid adenocarcinoma, gliomatosis peritonei, and carcinoid tumor in a patient with recurrent ovarian teratoma.

Gliomatosis peritonei (GP) describes the implantation of mature neuroglial tissue in the peritoneum and is usually associated with mature ovarian teratoma but is also found in cases of immature teratoma. We report the case of a patient with recurrent mature ovarian teratoma, GP, endometriosis (with malignant transformation), and carcinoid tumor, found at the time of hysterectomy for a primary endometrial adenocarcinoma. This unusual combination of tumor types has not been reported earlier. Metaplasia of the totipotential subcoelomic or submesothelial stem cells is a recognized pathway for the development of endometriosis. Evidence from molecular genetic studies suggests that a similar process of stem cell differentiation may explain at least some cases of GP. The coexistence (and colocalization) of endometriosis, GP, and carcinoid tumor in this case raises the possibility that peritoneal stem cells may occasionally show an even wider spectrum of aberrant differentiation. This has relevance for the assessment and management of patients with synchronous gynecologic tumors or presumed metastatic disease.