Faculty Bibliography

Internal mammary lymph nodes (IMLNs) account for approximately 10%-40% of the lymphatic drainage of the breast. Internal mammary lymph nodes measuring up to 10 mm are commonly seen on high-risk screening breast MRI examinations in patients without breast cancer and are considered benign if no other suspicious findings are present. Benign IMLNs demonstrate a fatty hilum, lobular or oval shape, and circumscribed margins without evidence of central necrosis, cortical thickening, or loss of fatty hilum. In patients with breast cancer, IMLN involvement can alter clinical stage and treatment planning. The incidence of IMLN metastases detected on US, CT, MRI, and PET-CT ranges from 10%-16%, with MRI and PET-CT demonstrating the highest sensitivities. Although there are no well-defined imaging criteria in the eighth edition of the American Joint Committee on Cancer Staging Manual for Breast Cancer, a long-axis measurement of ≥ 5 mm is suggested as a guideline to differentiate benign versus malignant IMLNs in patients with newly diagnosed breast cancer. Abnormal morphology such as loss of fatty hilum, irregular shape, and rounded appearance (which can be quantified by a short-axis/long-axis length ratio greater than 0.5) also raises suspicion for IMLN metastases. MRI and PET-CT have good sensitivity and specificity for the detection of IMLN metastases, but fluorodeoxyglucose avidity can be seen in both benign conditions and metastatic disease. US is helpful for staging, and US-guided fine-needle aspiration can be performed in cases of suspected IMLN metastasis. Management of suspicious IMLNs identified on imaging is typically with chemotherapy and radiation, as surgical excision does not provide survival benefit and is performed only in rare cases.

PURPOSE/OBJECTIVE:To compare heart and lung doses for adjuvant whole breast irradiation (WBI) between radiation plans generated supine with deep inspiratory breath hold (S-DIBH) and prone with free-breathing (P-FB) and examine the effect of breast volume (BV) on dosimetric parameters. MATERIALS/METHODS/METHODS:Patients with left breast DCIS or invasive cancer receiving adjuvant WBI were enrolled on a single-institutional prospective protocol. Patients were simulated S-DIBH and P-FB; plans were generated using both scans. Wilcoxon's Signed Rank and Rank Sum tests were used to compare intra-patient differences between plans for the entire cohort and within BV groups defined by tertiles. RESULTS:Forty patients were enrolled. Thirty-four patients are included in the analysis due to patient withdrawal or inability to hold breath. With WBI dose of 4005 - 4256 cGy, mean heart dose (MHD) was 80 cGy in S-DIBH, 77 cGy in P-FB (p=0.08). Mean ipsilateral lung dose (MLD) was 453 cGy in S-DIBH, 45 cGy in P-FB (p<0.0001). Mean and max LAD dose were 251 cGy and 551 cGy in S-DIBH respectively, 324 cGy (p=0.1) and 993 cGy in P-FB (p=0.3) respectively. Hot spot and separation was 109% and 22 cm in S-DIBH respectively, 107% and 16 cm in P-FB respectively (p<0.0001). For patients with smallest BV, S-DIBH improved MHD and LAD doses; for those with largest BV, P-FB improved cardiac dosimetry. With increasing BV, there was an increasing advantage of P-FB for MHD (p=0.05), and max (p=0.03) and mean (p=0.02) LAD dose, and the reduction in MLD, hot spot, and separation with P-FB increased (p<0.05). CONCLUSIONS:MHD did not differ between P-FB and S-DIBH, whereas MLD was significantly lower with P-FB. Analysis according to breast volume revealed improved cardiac dosimetry with S-DIBH for women with smallest BV and improved cardiac dosimetry with P-FB for women with larger BV, thereby providing a dosimetric rationale for using breast size to help determine the optimal positioning for WBI.

OBJECTIVE:To evaluate the effect of definitive radiotherapy dose on survival in patients with human papillomavirus positive oropharyngeal carcinoma. METHODS:Human papillomavirus positive oropharyngeal carcinoma patients staged T1-3 and N0-2c, who received definitive radiotherapy (fraction sizes of 180 cGy to less than 220 cGy), were identified from the National Cancer Database 2010-2014 and stratified by radiation dose (50 Gy to less than 66 Gy, or 66 Gy or more). RESULTS:A total of 2173 patients were included, of whom 124 (6 per cent) received a radiation dose of 50 Gy to less than 66 Gy. With a median follow up of 33.8 months, patients had a 3-year overall survival rate of 88.6 per cent (95 per cent confidence interval = 87.1-90.1 per cent). On multivariate Cox analysis, a radiotherapy dose of 50 Gy to less than 66 Gy (hazard ratio = 0.95, 95 per cent confidence interval = 0.52-1.74, p = 0.86) was not a predictor of increased mortality risk. CONCLUSION/CONCLUSIONS:Human papillomavirus positive oropharyngeal carcinoma patients had excellent outcomes with definitive radiotherapy doses of 50 Gy to less than 66 Gy. These results further support patients enrolling into clinical trials for radiation dose de-escalation.

Two commonly used whole breast irradiation (WBI) techniques, deep inspiration breath hold (DIBH) and prone positioning, are compared with regard to dosimetry and estimated late cardiac morbidity and secondary lung cancer mortality using published models. Forty patients with left-sided DCIS or breast cancer who underwent lumpectomy and required adjuvant WBI were enrolled on a prospective trial comparing supine DIBH (S-DIBH) with prone free breathing (P-FB) planning. Patients underwent CT simulation in both positions; two plans were generated for each patient. Comparative dosimetry was available for 34 patients. Mean cardiac and lung doses were calculated. Risk of death from ischemic heart disease (IHD), risk of at least one acute coronary event (ACE), and lung cancer mortality were estimated from published data. Difference between S-DIBH and P-FB plans was compared using paired two-tailed t test. Estimated mean risk of death from IHD by age 80 was 0.1% (range 0.0%-0.2%) for both plans (P = 1.0). Mean risk of at least one ACE was 0.3% (range 0.1%-0.6%) for both plans (P = .6). Mean lung cancer mortality risk was 1.4% (range 0.5%-15.4%) for S-DIBH and 1.0% (range 0.4%-9.8%) for P-FB (P = .008). Excess lung cancer mortality due to radiation was 0.5% (range 0.1%-6.0%) with S-DIBH and 0.0% (range 0.0%-0.4%) with P-FB (P = .008). Both S-DIBH and P-FB provide excellent cardiac sparing. Prone positioning results in lower lung dose than S-DIBH and leads to an absolute decrease of 0.5% in excess lung cancer mortality for patients receiving WBI.

BACKGROUND:Patients with an in-breast tumor recurrence (IBTR) after breast-conserving therapy have a high risk of distant metastasis and disease-related mortality. Classifying clinical parameters that increase risk for recurrence after IBTR remains a challenge. AIM/OBJECTIVE:To describe primary and recurrent tumor characteristics in patients who experience an IBTR and understand the relationship between these characteristics and disease outcomes. METHODS:Patients with stage 0-II breast cancer treated with lumpectomy and adjuvant radiation were identified from institutional databases of patients treated from 2003-2017 at our institution. Overall survival (OS), disease-free survival, and local recurrence-free survival (LRFS) were estimated using the Kaplan Meier method. We identified patients who experienced an isolated IBTR. Concordance of hormone receptor status and location of tumor from primary to recurrence was evaluated. The effect of clinical and treatment parameters on disease outcomes was also evaluated. RESULTS:= 0.004) decreased the risk of IBTR. CONCLUSION/CONCLUSIONS:Among patients with early stage breast cancer who had breast conserving surgery treated with adjuvant RT, ER/PR status and quadrant were highly concordant from primary to IBTR. Tumor size greater than 1.5 cm and use of adjuvant endocrine therapy were significantly associated with decreased risk of IBTR.