Introduction
Post colonoscopy colorectal cancer (PCCRC) is colorectal cancer diagnosed after a normal colonoscopy with no cancer found. In England, the rate of PCCRCs has been decreasing but remains around 6.5% for colonoscopies performed from 2011-20131. English study suggested that 80% of PCCRCs are avoidable2. We aim to analyse PCCRC cases using the local data and determine the demographics, nature of cancer and the cause of PCCRC.
Aims & Methods
The PCCRCS are identified following the linkage of Hospital Episode Statistics, Bowel cancer screening programme (BCSP) and cancer registry datasets. As new colorectal cancers are registered with the National Cancer Registration and Analysis Service (NCRAS), PCCRC cases will be identified. Each colorectal cancer (ICD-10 code C18-20) provisionally registered within the Hospital Episode Statistics dataset will be identified and determined whether a colonoscopy was performed within 6- 48 months before the diagnosis which failed to identify the cancer.
This audit includes patients diagnosed with PCCRC 6-48 months after a colonoscopy was performed in a single medical centre in England.
Once the cases had been confirmed, we reviewed the clinical, pathology and radiological findings of each case. We also looked at interval cancer which the World Endoscopy Organisation (WEO) defines as one diagnosed before the next recommended interval. Important to note that all interval cancers are PCCRCs but not all PCCRCs are interval cancer.
Results
39 cases were included and 29 were confirmed to be true PCCRC which fulfilled the above criteria. 7 did not meet the criteria. (2 index colonoscopies performed at other trusts, 3 missing data, 2 other types of cancers such as Neuroendocrine tumour and appendiceal tumour, 1 has <6 months to cancer diagnosis from index colonoscopy, 2 flexible sigmoidoscopy was performed as index colonoscopy to investigate per rectal bleeding but subsequent cancer was found in ascending colons).
52% (n=15) of patients were male with a median age of cancer diagnosis at 74 years old (range 22-84). In terms of PCCRC, 24% (n=7) presented via the National Bowel Screening Programme (BCSP), 14%(n=4) presented with per rectal bleeding, 7% (n=2) presented with abnormal imaging and the same proportion of patients presented due to anaemia, non-specific change in bowel habit, weight loss, diarrhoea, abdominal pain and surveillance for family history of gene mutation. 3% (n=1) were diagnosed after presenting for polypectomy and 3% (n=1) presented with intestinal obstruction.
In terms of investigations that led to PCCRC, 45% (n=13) were via 2-weeks-wait colonoscopy, 24% (n=7) were via National Bowel Screening Programme, 17% (n=5) were diagnosed by Computed Tomography (CT) imaging, 7% (n=2) via flexible sigmoidoscopy and 7% (n=2) was via surgically resected sample. Upon diagnosis of PCCRC, 7% (n=2) tested positive for Lynch syndrome, 24% (n=7) was tested but no marker was found and 69% (n=20) was not tested. In terms of size of PCCRC, 66% (n=19) had tumour size >2cm. 66% (n=17) of tumour size was determined by histopathological sample, 21 (n=6) via endoscopy, 3% (n=1) via CT imaging and 17% (n=6) was not known.
In terms of PCCRC staging, 48% (n=14) was Dukes’ A staging, 21% (n=6) was Dukes’ B, 7% (n=2) was Dukes’ C and 24% (n=7) was Dukes’ D. 83% (n=24) was planned for curative treatment and 17% (n=5) was planned for palliative treatment. 52% (n=16) had surgical resection only, 17% (n=29) had surgical resection and chemotherapy, 3% (n=11) had surgical resection and radiotherapy, 3% (n=1) had surgical resection, chemotherapy and radiotherapy, 7% (n=2) had chemotherapy and radiotherapy, 3% (n=1) had chemotherapy only, 3% (n=1) had endoscopic resection only and 7% (n=2) had no treatment.
In terms of the type of interval cancer, 14% (n=4) was non-interval A, 7% (n=2) was non-interval B, 66% (n=19) was non-interval C and 21% (n=4) was interval cancer. Important to note was 66% (n=19) had no further follow-up or test arranged due to adequate examination on the index endoscopy. 90% of index endoscopies report no difficulties. 75% (n=22) was due to clinician factors, 10% (n=3) was due to administrative errors such as booking delay and 10% (n=3) was due to patient factors such as patient’s decision and intercurrent illness.
Conclusion
The majority of the PCCRC had treatment with curative intent. Most PCCRC cases are due to clinician factors and measures needed to improve this. The high percentage of non-interval type C PCCRC would be explained by either a fast-growing cancer or a missed lesion since up to 90% of the index procedures reported no difficulty.
References
- Burr NE, Derbyshire E, Taylor J, et al. Variation in post-colonoscopy colorectal cancer across colonoscopy providers in English National Health Service: population-based cohort study. BMJ 2019;367:l6090. doi:10.1136/bmj.l6090
- Anderson R, Burr NE, Valori R. Causes of Post-colonoscopy Colorectal Cancers Based on World Endoscopy Organization System of Analysis. Gastroenterology Published Online First: January 2020. doi:10.1053/j.gastro.2019.12.03