Cardiac substructures exposure in left-sided breast cancer radiotherapy: Is the mean heart dose a reliable predictor of cardiac toxicity?

PURPOSE: This study aimed to assess radiation dose distribution to cardiac subvolumes in left-sided breast cancer radiotherapy (LBCRT) and to clarify whether the mean heart dose (MHD) reliably reflects cardiac substructures exposure. MATERIALS AND METHODS: Fifty women referred for adjuvant LBCRT were prospectively evaluated. All patients received 3D-conformal hypofractionated radiotherapy (40Gy delivered in 15 fractions of 2.67Gy±boost of 13.35Gy). Cardiac substructures were contoured using the F. Duane's cardiac atlas. Dose distribution to cardiac chambers, left main (LM), left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA)) was assessed. Dosimetric associations were analysed. RESULTS: The mean MHD was 3.08Gy (EQD2=3.67Gy). The mean Dmean/Dmax LAD was 11.45Gy (EQD2=13.64Gy)/29.5Gy (EQD2=35.15Gy). Low doses were delivered to LM, LCx, and RCA (Dmean≤1.3Gy). The left ventricle (LV) was the most exposed cardiac chamber with Dmean/Dmax of 4.78Gy/37Gy. The strongest correlation with MHD was found for Dmean LAD (r=0.81). For every 1Gy increase in MHD, Dmean LAD rose by 3.4Gy. However, the proportion of variance in Dmean LAD predictable from MHD was moderate (R2=0.65). For all other cardiac substructures, R2 values were<0.7. CONCLUSION: Our study showed high exposure of LAD and LV in LBCRT. With poor predictive value, MHD may underestimate doses to cardiac substructures. For optimal heart sparing radiotherapy, we recommend to consider LV and LAD as separate organ at risk.

Nasopharyngeal carcinoma with cutaneous metastases.

INTRODUCTION: Cutaneous metastases from nasopharyngeal carcinoma are extremely rare and associated with a poor prognosis. CASE REPORTS: We retrospectively reviewed 820 patients with nasopharyngeal carcinoma treated over a 20-year period in the radiotherapy department of Farhat Hached hospital in Sousse and Ibn Khaldoun Medical centre, Hammam Sousse. Two of these patients presented cutaneous metastases. The skin lesions appeared during radiotherapy and 3 months after treatment of the primary tumour. Cutaneous metastases present as multiple painless nodules and erythematous plaques. Cutaneous metastases were associated with other metastatic sites (liver, bone). One patient received chemotherapy. Both patients died in a context of rapidly progressive disease. DISCUSSION: Nasopharyngeal carcinoma with cutaneous metastases is a rapidly fatal disease. In the light of these two cases and a review of the literature, patients with this disease are aged between 30 and 63 years with a marked male predominance. Cutaneous metastases are correlated with a more advanced primary tumour. The main sites are the trunk and scalp. There is no standard treatment modality for this disease and survival does not exceed 9 months.