Surveillance Computed tomography scan– Is there a role at five years in post curative resection of colorectal cancer?

Objectives: There are signifi cant worldwide variations in the use of Computed Tomography (CT) scan for postoperative surveillance of patients after curative treatment for colorectal cancer. The NICE (National Institute of Clinical Excellence) guidelines (CG131/NG151) recommends the use of 2 CT scans of chest, abdomen and pelvis in the fi rst three years following curative resection. Our hospital policy was to perform a third scan at fi ve years prior to discharge from follow-up. This study aimed at determining the oncological benefi t of the additional scan at 5-years post-surgery. This current audit result will adds evidence to the planned introduction of stratifi ed follow-up. Method: Retrospective analysis of CT scans performed at fi ve years post curative resection for colorectal adenocarcinoma in a single UK Trust, between December 2015 and December 2018. Results: A total of 200 consecutive patients (133 male, 67 female; median age 73 years) were reviewed. No patients (0%) were found to have new colorectal recurrence at Year-5 scan. One patient underwent an expedited CT scan for symptoms and presence of suspicious fi ndings on previous CT scans. The calculated sensitivity of CT scan for excluding colorectal recurrence was 100% with a specifi city of 97.5% Conclusion: The additional Year-5 CT scan beyond NICE recommended two scans did not demonstrate any signifi cant clinical benefi t in the detection of recurrence or metastatic colorectal cancer. In addition, CT scans expose patients to additional radiation risks and adds further burden to a resource-limited NHS. Retrospective Study Surveillance Computed tomography scan– Is there a role at fi ve years in post curative resection of colorectal cancer? Ishani Mukhopadhyay1*, Dariush Kamali2 and Venkatesh Shanmugam3 1BM, BS, University Hospital of North Tees and Hartlepool, Hardwick Road, Stockton-On-Tees, TS19 8PE, UK 2BmedSci, BM, BS, MmedED, FRCS (Eng), Darlington Memorial Hospital, Woodlands Road, Darlington, DL3 6HX, UK 3University Hospital of North Tees and Hartlepool, Hardwick Road, Stockton-On-Tees, TS19 8PE, UK Received: 21 September, 2020 Accepted: 09 October, 2020 Published: 10 October, 2020 *Corresponding author: Dr. Ishani Mukhopadhyay, BM, BS, University Hospital of North Tees and Hartlepool, Hardwick Road, Stockton-On-Tees, TS19 8PE, UK, E-mail: https://www.peertechz.com


Introduction
There are approximately 1.8 million new diagnosis of colorectal cancer (CRC) annually. The fi ve year survival rate is >90% if diagnosed at an early stage [1]. Early diagnosis with absent metastasis carries a a relatively good prognosis. It is well known that surgical resection is the defi nitive treatment option for operable colorectal cancers, with the addition of adjuvant or neo-adjuvant chemo and/or radiotherapy to achieve remission for advanced tumour with or without nodal involvement [2].
Unfortunately 30 to 40% of colorectal cancers recur within Citation: Mukhopadhyay  the fi rst fi ve years of surgical resection; the fi rst two years being the most crucial time [3]. Regular follow-up is therefore necessary to detect early recurrence and offers potential opportunity to salvage it. Combination of the follow-up tools help with this early detection of recurrence. This includes clinical review of the patients along with Carcino-embryonic antigen (CEA) monitoring and regular imaging to detect recurrence in addition to the endoscopic surveillance at the end of one year and four years post-surgery. Computed Tomography (CT) has been considered a sensitive mean to image recurrence within the limits of the scan for the size of the recurrent lesions [4]. However, there are signifi cant worldwide variation in the follow-up protocol for these patients, particularly the CT scan surveillance (Figure 1) [5]. While the NICE (National Institute for Health and Clinical Excellence -UK) guidelines (CG131/NG151) recommends the use of 2 CT scans over the fi rst three years following curative treatment, the American Society of Colon and Rectal Surgeons (ASCRS) recommends the use of annual CT imaging for fi ve years [6,7].
Several NHS (National Health Service) Trusts within the UK continue to pursue more intensive follow-up protocols deviating from the national recommendation [8]. This study was performed in a Trust where a further CT scan at Year-5 was routinely performed prior to the patient discharge from the protocol follow-up. We therefore aimed to study the oncological benefi t of performing a CT scan at 5 years post curative resection of colorectal cancer (CRC) in addition to the standard national recommendation.
Information collected on patient demographics included age, sex, tumour site, TNM staging and neo-adjuvant treatment details (down-staging treatment). Histology results (tumour grade, completeness of resection and any adverse features) were also recorded. Patients with a diagnosis other than adenocarcinoma and with metastasis (TxNxM1) on initial diagnosis were excluded. The calculated sensitivity of CT scan to exclude colorectal recurrence was 100% with a specifi city of 97.5%. The positive predictive value (PPV) and negative predictive value (NPV) were 16.67% and 100%, respectively. This confi rms the reliability of the CT scan and adds value to the decision making in the follow-up protocol.

Discussion
Over the past decade, several studies have been conducted to establish the optimal and safe followup protocol for colorectal cancer resections. Traditionally, it was believed that more intensive strategies would aim to detect recurrence at an earlier stage particularly asymptomatic patients, thus allowing timely intervention for salvage and a better survival benefi t [9,10]. However, a systematic review conducted by Jeffrey, et al. found that this was not associated with improved survival rate [4].

Radiation risk from CT scan
A CT scan of chest, abdomen and pelvis (CT CAP) exposes a patient to 17 mSv (millisieverts) ionizing radiation; considered to be equivalent to fi ve years natural background radiation [14]. Studies over the past two decades have highlighted the risks of radiation-induced carcinogenesis. Although there is limited availability of experimental data. The Bier report (latest published Bier VII) analysed data from a cohort of Japanese atomic bomb survivors at Hiroshima and Nagasaki to derive risk models and calculated lifetime attributable risk (LAR; additional cancer risk beyond baseline cancer risk) [15]. While a single CT scan does not necessarily expose a patient to a signifi cant amount of radiation, multiple exposure can increase the cumulative risk signifi cantly. Furthermore, exposed organs and their individual sensitivity to radiation leading to CT scan At least 2 in fi rst 3 years.
Annually for 5 years.
At Year-1, Year-2 and fi nal CT scan at Year-5 prior to discharge from follow-up.
Colonoscopy 1 year post resection followed by 5-yearly surveillance.
1 year post resection followed by another in 3-5 years.
1 year post resection followed by another one at Year-4 and every 5years until the age of 75 years unless any polyp detection changes the frequency (BSG guidelines*).

Cost-effectiveness
In addition to this, our hospital estimated current cost for a