Prognostic value of positron emission tomography/computed tomography for adjuvant chemotherapy of colon cancer

Clinical significance of the maximum standardized uptake value on positron emission tomography to predict treatment response and outcomes in patients with rectal cancer undergoing neoadjuvant chemoradiotherapy

PURPOSES

The association between the reduction rate of the maximum standardized uptake value (SUVmax) on positron emission tomography (PET) during neoadjuvant chemoradiotherapy (NACRT) and the prognosis in patients with locally advanced rectal cancer is unknown.

METHODS

We retrospectively analyzed 62 patients with locally advanced rectal cancer who underwent curative surgery after NACRT at Kobe University between 2008 and 2021. The SUVmax reduction rate was calculated from preoperative and postoperative PET scans, and its association with the prognosis was investigated.

RESULTS

The cutoff value for SUVmax reduction rate was 61.5%. Twenty patients had an SUVmax reduction rate > 61.5% (SUV responder group) and 38 patients had an SUVmax reduction rate ≤ 61.5% (SUV nonresponder group). Regarding pathological outcomes, the rate of a good histological response was significantly higher in the SUV responder group than in the SUV nonresponder group (80.0% vs. 21.1%, p < 0.001). Both the overall (OS) and relapse-free survival (RFS) rates were significantly better in the SUV responder group than in the SUV nonresponder group (OS, p = 0.035; RFS, p = 0.019). In the SUV responder group, only 1 case of recurrence was observed, with a median follow-up period of 56 months.

CONCLUSION

The rate of SUVmax reduction during NACRT might predict the long-term prognosis of patients with locally advanced rectal cancer.

Diagnostic accuracy of CT for local staging of colon cancer: A nationwide study in the Netherlands

OBJECTIVE

To determine the accuracy of computed tomography (CT)-based staging in selecting high-risk colon cancer patients who would benefit from neoadjuvant chemotherapy while avoiding overtreatment.

METHODS

Data of adult patients diagnosed with non-metastatic primary colon cancer in 2005-2020, who underwent surgical resection without neoadjuvant chemotherapy, were retrospectively collected from the Netherlands Cancer Registry. Agreement between clinical and pathological evaluation for each T and N stage was calculated. Sensitivity and specificity analyses were conducted to predict T3-T4 and N1-N2 stages, with histopathology as the reference standard.

RESULTS

Data from 44,471 patients (median age, 71 years, 50% female) were evaluated. We included 38,915 patients with complete T stage and 39,565 patients with complete N stage for analyses. The overall clinical-pathological agreement for T stage was 59% and for N stage 57%. The sensitivity and specificity of CT to detect T3-T4 tumours were 80% (95% confidence interval (CI): 0.79, 0.80) and 76% (95% CI: 0.75, 0.77), respectively, with a positive predictive value (PPV) of 92% (95% CI: 0.92, 0.92). The sensitivity and specificity of CT to detect N1-N2 category were 62% (95% CI: 0.61, 0.63) and 70% (95% CI: 0.69, 0.71), respectively, with PPV 60% (95% CI: 0.59, 0.60).

CONCLUSION

CT-based staging shows limited accuracy in selecting colon cancer patients who would benefit from neoadjuvant therapy without risking overtreatment. Detection of lymph node metastases with CT remains unreliable.

Relationship between CT signs and the expression of miR-146a in colon cancer

Our study investigated the relationship between CT signs of colon cancer and the expression of miR-146a, to evaluate their predictive value in early diagnosis and of colon cancer. A total of 216 patients with colon cancer who were admitted to the Department of Hematology and Oncology in Yingcheng Hospital, the Second Hospital of Shandong University in Zhaoyuan City from January 2013 to March 2017 were selected as the study group. At the same time, 150 patients with benign colitis were also included to serve as the control group. CT scan was performed for patients in both the study and control groups. The expression of miR-146a in serum of patients in the study and control groups was detected by RT-qPCR, and of CT signs and miR-146a expression were analyzed. The relative expression level of miR-146a in peripheral blood of study group was significantly lower than that of the control group (t=12.180, p=0.001). Sensitivity and specificity of combined detection of CT and miR-146a in the study and control groups were 91.4 and 93.6%, respectively, which were higher than those of the single test (p<0.05). Among CT signs of study group, luminal wall, cavity and diameter changes, as well as size of tumor and surrounding tissues showed no significant correlation with the expression of miR-146a (p>0.05). The expression level of miR-146a in patients with high-risk of invasion was significantly higher than that in patients with low-risk of invasion (t=4.791, p=0.001). The expression level of miR-146a in lymph node metastasis was significantly lower than that in non-lymph node metastasis (t=3.104, p=0.002). miR-146a may be involved in the development and progression of colon cancer. Combined detection of CT and miR-146a may enhance the sensitivity and specificity of the diagnosis of colon cancer, and may provide a good predictive value for invasion and metastasis of colon cancer.