The potential predictive value of MRI and PET-CT in mucinous and nonmucinous rectal cancer to identify patients at high risk of metastatic disease

OBJECTIVE

To correlate imaging parameters from baseline MRI diffusion-weighted imaging (DWI) and fludeoxyglucose (FDG) positron emission tomography (PET)-CT with synchronous and metachronous metastases in mucinous carcinoma (MC) and non-mucinous carcinoma (NMC) rectal cancer.

METHODS

111 patients with extraperitoneal locally advanced rectal cancer, who underwent pelvic MRI, DWI and FDG PET-CT, were stratified into MC (n = 23) and NMC (n = 88). We correlated adverse morphologic features on MRI [mT4, mesorectal fascia involvement, extramural venous invasion (mEMVI), mN2] and quantitative imaging parameters [minimum apparent diffusion coefficient (ADC_min), maximum standardized uptake value, total lesion glycolysis, metabolic tumour volume, T₂ weighted and DWI tumour volumes] with the presence of metastatic disease. All patients underwent pre-operative chemoradiation therapy (CRT); 100/111 patients underwent surgery after CRT and were classified as pathological complete response (PCR) and no PCR [tumour regression grade (TRG)1 vs TRG2-5] and as ypN0 and ypN1-2. Median follow-up time was 48 months. Metastases were confirmed on FDG PET-CT and contrast-enhanced multidetector CT.

RESULTS

The percentage of mucin measured by MRI correlates with that quantified by histology. On multivariate analysis, the synchronous metastases were correlated with mEMVI [odds ratio (OR) = 21.48, p < 0.01] and low ADC_min (OR = 0.04, p = 0.038) in NMC. The difference of metachronous recurrence between the MC group (10-90% mucin) and NMC group was significant (p < 0.01) (OR = 21.67, 95% confidence interval 3.8-120.5). Metachronous metastases were correlated with ypN2 (OR = 8.24, p = 0.01) in MC and in NMC. In NMC, mEMVI correlated with no PCR (p = 0.018) and ypN2 (p < 0.01).

CONCLUSION

mEMVI could identify patients with NMC, who are at high risk of synchronous metastases. The MC group is at a high risk of developing metachronous metastases. Advances in knowledge: Patients at high risk of metastases are more likely to benefit from more aggressive neoadjuvant therapy.

Role of the Apparent Diffusion Coefficient in the Prediction of Response to Neoadjuvant Chemotherapy in Patients With Locally Advanced Breast Cancer

BACKGROUND

We evaluated the diagnostic performance of the baseline diffusion weighted imaging (DWI) and the apparent diffusion coefficient (ADC) in the prediction of a complete pathologic response (pCR) to neoadjuvant chemotherapy (NAC) in patients with breast cancer stratified according to the tumor phenotype.

PATIENTS AND METHODS

We retrospectively studied 225 patients with stage II, III, and IV breast cancer who had undergone contrast-enhanced magnetic resonance imaging (MRI) and DWI before and after NAC, followed by breast surgery.

RESULTS

The tumor phenotypes were luminal (n = 143; 63.6%), triple-negative (TN) (n = 37; 16.4%), human epidermal growth factor receptor 2 (HER2)-enriched (n = 17; 7.6%), and hybrid (hormone receptor-positive/HER2(+); n = 28; 12.4%). After NAC, a pCR was observed in 39 patients (17.3%). No statistically significant difference was observed in the mean ADC value between a pCR and no pCR in the general population (1.132 ± 0.191 × 10(-3) mm(2)/s vs. 1.092 ± 0.189 × 10(-3) mm(2)/s, respectively; P = .23). The optimal ADC cutoff value in the general population was 0.975 × 10(-3) mm(2)/s (receiver operating characteristic [ROC] area under the curve [AUC], 0.587 for the prediction of a pCR). After splitting the population into subgroups according to tumor phenotype, we observed a significant or nearly significant difference in the mean ADC value among the responders versus the nonresponders in the TN (P = .06) and HER2(+) subgroups (P = .05). No meaningful difference was seen in the luminal and hybrid subgroups (P = .59 and P = .53, respectively). In contrast, in the TN and HER2(+) subgroups (cutoff value, 0.995 × 10(-3) mm(2)/s and 0.971 × 10(-3) mm(2)/s, respectively), we observed adequate ROC AUCs (0.766 and 0.813, respectively).

CONCLUSION

The pretreatment ADC value is not capable of predicting the pCR in the overall population of patients with locally advanced breast cancer. Nonetheless, an ameliorated diagnostic performance was observed in specific phenotype subgroups (ie, TN and HER2(+) tumors).

Magnetic resonance imaging features in triple-negative breast cancer: comparison with luminal and HER2-overexpressing tumors

BACKGROUND

It has been ascertained that triple-negative (TN) breast cancer is characterized by an aggressive clinical course and a poor prognosis. The purpose of our study was to compare the magnetic resonance imaging (MRI) features of the 3 major different breast cancer subtypes (TN, luminal, and human epidermal growth factor receptor 2 [HER2]-overexpressing) and to suggest the criteria that might predict TN phenotype.

MATERIALS AND METHODS

From October 2007 to April 2011, we studied 77 patients with histologically confirmed TN breast cancer who underwent breast MRI. We randomly included 148 patients with non-TN breast cancer (110 luminal and 38 HER-overexpressing) as a control group. We evaluated the clinicopathologic data, the MRI morphologic and kinetic features, the signal intensity on T2-weighted images, and the apparent diffusion coefficient (ADC).

RESULTS

Our results confirmed that TN tumors are more aggressive, are usually diagnosed at a younger age compared with the other study groups, and show benign morphologic features with MRI. Backward stepwise logistic regression identified some parameters as independent predictors of TN-type lesions: age, size, shape, presence of edema, and infiltrative characteristics. The receiver operating characteristic (ROC) curve, built with 4 of 5 these factors as criteria to predict TN status, showed a 0.664 area under the curve (AUC) value (sensitivity 58.4%, specificity 73.2%). The inclusion of the fifth criterion showed a 0.699 AUC value (sensitivity, 49.4%; specificity, 89.4%).

CONCLUSION

We identified the clinicoradiologic parameters that are independent predictors of TN breast lesions, which might be helpful for earlier prediction of the TN status of a breast lesion.