A. Amin Darwish (Alexandria, Egypt)
University of Alexandria - Faculty of MedicineAuthor Of 2 Presentations
78P - A dosimetric study of the non-intended irradiation to the internal mammary lymph nodes during locoregional radiotherapy to the breast
Abstract
Background
Adjuvant radiotherapy (RT) in breast cancer is an essential part of the local treatment of the breast and regional lymph nodes. Whether the internal mammary lymph nodes (IMNs) should be included in the RT field is controversial due to limited data. The low incidence of IMNs recurrence may be due to the incidental dose received. The aim of this study is to estimate the incidental irradiation dose recieved by IMNs during 3DCRT and whether this dose correlates with IMNs recurrence.
Methods
This retrospective dosimetric study included 137 cases treated at our institution during the year 2016-2017. Inclusion criteria: patients who underwent either MRM or BCS and were candidate to receive adjuvant locoregional radiotherapy (without intended inclusion of IMLNS in the radiotherapy field). For this study, the IMNs was contoured through the topography of the internal thoracic vessels starting cranially at the superior border of the first rib, caudally at the cranial end of the fourth rib. IMNs mean dose (IMDmean), maximum dose (IMN max) and minimum dose (IMN min) were obtained. In addition, the ipsilateral lung volume that received ≥20 Gy (V20), heart mean dose (for patients with left side tumors only), parasternal soft tissue thickness and the distance between the medial tangent field border and the mid-line were measured (both measured at level of the third rib).
Results
In all cases, PTV IM was covered by less than 95% of the prescribed dose. The IMLs mean dose was 28.50% (SD 20.71%) of the prescribed dose. There was no significant difference between the right and left side regarding IMND mean, lung v20 or heart mean dose. Six patients (4.37%) had IMNs recurrences, the IMLs mean dose in all of them was less than 28% of the prescribed dose. IMLs mean dose less than 28% significantly predicted IMLs recurrences (P value=0.05). IMN mean dose significantly correlated with the mean distance between mid line and medial tangent field border (0.8 cm) with P value< 0.0001.
Conclusions
IMN receives considerable incidental dose of radiation. The required dose to prevent against IMN recurrence may be lower than the prescribed dose for other nodal areas. Prospective trials are needed to determine the optimum dose and indication to irradiate IMN.
Legal entity responsible for the study
Alexandria University, Egypt.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
136P - The incidence and prognostic impact of obesity in young Egyptian breast cancer patients
Abstract
Background
The breast cancer (BC) incidence of young women in Africa and the Middle East is higher than that of the western population. Growing evidence shows a global increase in obesity incidence. Both obesity and young age are associated with poor survival in BC. Thus, it is relevant to address this question in this population.
Methods
We retrospectively reviewed 720 female BC patients ≤40 years who had the weight and height data in two centers in Alexandria – Egypt. The body mass index (BMI) was categorized according to WHO groups into underweight – UW (BMI 18.5 kg/m2), normal weight - NW (BMI ≥18.5 to < 25kg/m2), overweight – OW (BMI ≥25 to < 30kg/m2), obese – Ob (BMI >30 kg/m2). We determined the obesity incidence, clinicopathological features, and the impact of obesity on survival by Kaplan Meir and Cox regression.
Results
The median follow-up was 44 months (1 - 143). The BMI distribution was UW - 1.7% (12), NW - 11.1% (80), OW - 26.8% (193), Ob - 60.4% (435); more than 85% were Ob/OW. The median age in UW/NW, OW, and Ob was 34, 35, and 37 years, respectively. Ob patients were significantly older, p < 0.001. The mean tumor size was 3.4cm in UW/NW, 3.7cm – OW, and 3.7cm - Ob. The Ob had a significantly higher incidence of high nodal involvement (44%; p − 0.023), and significantly estrogen/progesterone negative (21.2%; p − 0.016). Ki-67 was higher in Ob (57.4%) and OW (74%) than UW/NW (50%); p – 0.222. The distant relapse rates were insignificantly higher in Ob - 25.7% and OW - 25.5% than UW/NW - 20.2%; p – 0.352. There were no significant differences in the mean disease-free survival (CI: 81 – 96; p-0.692) and the overall survival (CI:120 – 124; p-0.186). In the multivariate analysis and cox regression, obesity did not impact survival.
Conclusions
There is an alarmingly high incidence of Ob/OW among young Egyptian BC patients. Our results confirm that Ob patients have more aggressive features than UW/NW. Nevertheless, our results suggest that, despite the poor prognostic factors characteristics, higher BMI did not worsen the survivals.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.