Next Generation intraoperative Lymph node staging for Stratified colon cancer surgery (GLiSten): a multicentre, multinational feasibility study of fluorescence in predicting lymph node-positive disease

Excerpt

Background: 5-aminolevulinic acid (5-ALA) is used for fluorescence diagnosis (FD) in neurological, gynaecological and urological malignancies. The Medical Research Council/Efficacy and Mechanism Evaluation (EME) programme/National Institute for Health Research’s Next Generation intraoperative Lymph node staging for Stratified colon cancer surgery (GLiSten) study investigated its use to predict lymph node (LN)-positive disease in colon cancer as an aid to stratified surgery.

Objectives: The primary objective was to optimise the dose of oral 5-ALA for intraoperative FD of metastatic LNs in colon cancer. Secondary objectives included standardisation of pre-operative computerised tomography (CT) LN reporting, intraoperative fluorescence detection, surgical resection with D3 lymphadenectomy and histopathological examination of resected specimens.

Design: This was a feasibility study to determine optimal strategies for 5-ALA positive LN detection. Patients with locally advanced disease identified using the Fluoropyrimidine, Oxaliplatin and Targeted-Receptor pre-Operative Therapy for patients with high-risk, operable colon cancer (FOxTROT) criteria were recruited from two sites between October 2013 and June 2015. Cohort 1 received 20 mg/kg and cohort 2 received 30 mg/kg of oral 5-ALA, 1–6 hours preoperatively. Laparoscopic assessment of fluorescence was performed using the Storz D-Light system (KARL STORZ GmbH & Co. KG; Tuttlingen, Germany), with marking of fluorescent LNs, followed by oncological resection. The specimen was subjected to histological analysis with step sectioning of marked fluorescent LNs. Progression to an evaluation phase using the optimal dosing schedule was dependent on positively identifying at least 2 out of 10 patients with metastatic LN disease in either cohort.

Results: A total of 44 patients were recruited with a male to female ratio of 26 : 18 and a mean age of 71 years (range 52–88 years). Cohort 1 consisted of 18 patients, of whom six had fluorescent primary cancers and three of these had fluorescent LNs. One out of 10 patients with metastatic LN disease had a fluorescent involved LN. Cohort 2 consisted of 26 patients, of whom eight had fluorescent primary cancers and four of these had fluorescent LNs. None of the fluorescent LNs contained disease in this cohort. No serious adverse events (SAEs) occurred but two mild, self-limiting, photosensitivity reactions were observed in cohort 2. The sensitivity and specificity for 5-ALA detection of LN-positive disease were: cohort 1 11.1%, 75%; and cohort 2 0%, 75%.

Limitations: This was a feasibility study exploring the use of 5-ALA for LN disease in a select cohort of patients with advanced colorectal cancer. The study population was small and generalisation to other cancers is not possible. The study was limited by the ability to determine LN-positive patients on the basis of pre-operative CT staging, which is often inaccurate, resulting in our cohorts containing several patients without LN disease.

Conclusions: 5-ALA fluorescent diagnosis has poor sensitivity for discriminating LN-positive colon cancer. Its use as an aid to stratified colon cancer surgery is not supported. No SAEs were observed, suggesting that photosensitisers may be useful for intraoperative FD.

Future work: 5-ALA has poor sensitivity for detecting LN metastases and cannot be recommended for intraoperative staging. Other, more sensitive fluorescent probes are required if this strategy is to be used.

Study registration: Current Controlled Trials ISRCTN79949827 and EudraCT number 2012–002623–15.

Funding details: This project was funded by the EME programme, a Medical Research Council and National Institute for Health Research partnership.