Abstract
BackgroundThe presence of lateral pelvic lymph node (LLN) metastasis is an essential prognostic factor in rectal cancer patients. Thus, preoperative diagnosis of LLN metastasis is clinically important to determine the therapeutic strategy. The aim of this study was to evaluate the efficacy of preoperative positron emission tomography/computed tomography (PET/CT) in the diagnosis of LLN metastasis.MethodsEighty-four patients with rectal cancer who underwent LLN dissection at Osaka University were included in this study. The maximum standardized uptake value (SUVmax) of the primary tumor and LLN were preoperatively calculated using PET/CT. Simultaneously, the short axis of the lymph node was measured using multi-detector row computed tomography (MDCT). The presence of metastases was evaluated by postoperative pathological examination.ResultsOf the 84 patients, LLN metastases developed in the left, right, and both LLN regions in 6, 7, and 2 patients, respectively. The diagnosis of the metastases was predicted with a sensitivity of 82%, specificity of 93%, positive predictive value of 58%, negative predictive value of 98%, false positive value of 7%, and false negative value of 18% when the cutoff value of the LLN SUVmax was set at 1.5. The cutoff value of the short axis set at 7 mm on MDCT was most useful in diagnosing LLN metastases, but SUVmax was even more useful in terms of specificity.ConclusionsThe cutoff value of 1.5 for lymph node SUVmax in PET is a reasonable measure to predict the risk of preoperative LLN metastases in rectal cancer patients.
Highlights
The presence of lateral pelvic lymph node (LLN) metastasis is an essential prognostic factor in rectal cancer patients
The patients were excluded from the study if 1) they had not undergone preoperative 18F-FDG Positron emission tomography (PET)/computed tomography (CT) scans (n = 13), 2) they had been diagnosed with locally recurrent rectal cancer (n = 11), 3) they had been diagnosed as squamous cell carcinoma (n = 2) and 4) the patient who underwent unilateral selective lateral lymph node dissection (LLND) (n = 2)
We excluded 13 patients who did not undergo preoperative 18F-FDG positron emission tomography/ computed tomography (PET/CT) scans, 11 who were diagnosed with locally recurrent rectal cancer, 2 who were diagnosed as squamous cell carcinoma and 2 who underwent unilateral selective LLND
Summary
The presence of lateral pelvic lymph node (LLN) metastasis is an essential prognostic factor in rectal cancer patients. The presence of lateral pelvic lymph node (LLN) metastasis is an important prognostic factor in patients with lower rectal cancer [1]. In Japan, LLN metastases are considered a local metastasis, and TME with lateral lymph node dissection (LLND) is performed as the standard surgical procedure for advanced lower rectal cancer. According to some reports, this surgical procedure has several potential disadvantages such as hemorrhage, prolonged surgical time, and risk of complications such as dysuria and sexual dysfunction [8, 9] Considering these potential complications, accurate preoperative prediction of LLN metastasis is required to identify the patients who are suitable for LLND. No definitive conclusions have been drawn regarding the optimal cutoff value
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