Evaluation of skin dose and skin toxicity in patients undergoing intraoperative radiotherapy for early breast cancer.

PURPOSE: This study aims to evaluate in vivo skin dose delivered by intraoperative radiotherapy (IORT) and determine the factors associated with an increased risk of radiation-induced skin toxicity. METHODOLOGY: A total of 21 breast cancer patients who underwent breast-conserving surgery and IORT, either as IORT alone or IORT boost plus external beam radiotherapy (EBRT), were recruited in this prospective study. EBT3 film was calibrated in water and used to measure skin dose during IORT at concentric circles of 5 mm and 40 mm away from the applicator. For patients who also had EBRT, the maximum skin dose was estimated using the radiotherapy treatment planning system. Mid-term skin toxicities were evaluated at 3 and 6 months post-IORT. RESULTS: The average skin dose at 5 mm and 40 mm away from the applicator was 3.07 ± 0.82 Gy and 0.99 ± 0.28 Gy, respectively. Patients treated with IORT boost plus EBRT received an additional skin dose of 41.07 ± 1.57 Gy from the EBRT component. At 3 months post-IORT, 86% of patients showed no evidence of skin toxicity. However, the number of patients suffering from skin toxicity increased from 15% to 38% at 6 months post-IORT. We found no association between the IORT alone or with the IORT boost plus EBRT and skin toxicity. Older age was associated with increased risk of skin toxicities. A mathematical model was derived to predict skin dose. CONCLUSION: EBT3 film is a suitable dosimeter for in vivo skin dosimetry in IORT, providing patient-specific skin doses. Both IORT alone and IORT boost techniques resulted in similar skin toxicity rates.

Gastrointestinal tract metastasis presenting as intussusception in invasive lobular carcinoma of the breast: A case report.

INTRODUCTION: Breast cancer metastasis to the gastrointestinal (GI) tract is rare and occurs more frequently in invasive lobular carcinoma. Patients may be asymptomatic or present with variable vague symptoms that may be mistakenly attributed to side effects of chemotherapy or other benign GI diseases. Treatment follows the principles of systemic disease and includes hormonal therapy, chemotherapy and signal transduction inhibitors, with surgical intervention indicated for complications such as obstruction, perforation and hemorrhage. PRESENTATION OF CASE: We present the case of a female patient with a history of invasive lobular breast carcinoma who had undergone mastectomy and axillary dissection, followed by chemoradiotherapy. Over the next nine years, she developed ovarian and bone metastases for which appropriate treatment was provided. A right iliac fossa mass was discovered during routine clinic review, though she remained asymptomatic. Computed tomography scan showed ileocecal intussusception. Histopathological examination of the right hemicolectomy specimen following emergency surgery confirmed metastatic invasive lobular carcinoma to the GI tract. DISCUSSION: GI tract metastasis may present 30 years after the primary breast cancer. Up to 20% of patients may be asymptomatic as shown by Montagna et al. When present, symptoms are commonly non-specific and vague. Histological diagnosis is challenging. GI metastasis typically appears as intramural infiltration of the bowel wall by small cells arranged in cords. CONCLUSION: It is important to maintain a suspicion for GI tract metastasis in breast cancer patients who present with abdominal mass or GI symptoms, as this aids in prompt institution of accurate and appropriate management.