Guideline sources The following summarized guidelines for the management of ductal carcinoma in situ are prepared by our editorial team based on guidelines from the American Society for Radiation Oncology (ASTRO/ASCO 2016). 1 4 4 4 5 Definition DCIS of the breast is the proliferation of malignant epithelial cells within the mammary ductal system without involving the basement membrane or invasion into the surrounding stroma. 4 Epidemiology DCIS is caused mainly by chromosomal imbalances including loss of heterozygosity and overexpression of the HER2 (HER2)/neu proto-oncogene and mutation in the p53 tumor suppressor gene. 4 Disease course DCIS is clinically silent in most cases; however, a breast lump or bloody nipple discharge may be present. Progression may lead to invasive breast cancer. 4 Prognosis and risk of recurrence DCIS is not associated with any excess risk of death, except in women aged < 50 years with a standard mortality ratio of 3.44 (95% CI 1.85-6.40). 5 Guidelines https://web.pathway.md/diseases/reclNi2rcyjrE9A7m 1/3 6/29/23, 10:21 PM Ductal carcinoma in situ Pathway 1. Medical management Systemic therapy: as per ASCO 2016 guidelines, rates of ipsilateral breast tumor recurrence are reduced with endocrine therapy, but there is no evidence of an association between endocrine therapy and negative margin width. B 2. Therapeutic procedures Whole-breast radiation therapy: As per ASCO 2016 guidelines: A positive margin, defined as ink on DCIS, is associated with a signicant increase in ipsilateral breast tumor recurrence; the use of whole breast radiotherapy does not nullify this increased risk. A Avoid choosing whole-breast radiotherapy delivery technique, fractionation, and boost dose on the basis of negative margin width. D 3. Surgical interventions Surgical excision: as per ASCO 2016 guidelines, higher rates of ipsilateral breast tumor recurrence are reported with treatment with excision alone, regardless of margin width, than treatment with excision and whole breast radiotherapy. A Clinical findings Patient demographics Symptoms Elderly age Breast lump Breast pain Past medical history Changes to the breast or nipple that are different from the ones present on period Obesity Past obstetric history Medication history Early menarche HRT Late first pregnancy Hormonal contraceptives Late menopause Family history Social history Breast cancer Alcohol consumption Ovarian cancer Physical inactivity Breast exam Genetic testing Inverted nipple Brca1 gene mutation Nipple discharge Brca2 gene mutation https://web.pathway.md/diseases/reclNi2rcyjrE9A7m 2/3 6/29/23, 10:21 PM Ductal carcinoma in situ Pathway References 1. Morrow M, Van Zee KJ, Solin LJ et al. Society of Surgical Oncology-American Society for Radiation Oncology-American Society of Clinical Oncology Consensus Guideline on Margins for Breast- Conserving Surgery With Whole-Breast Irradiation in Ductal Carcinoma In Situ. J Clin Oncol. 2016 Nov 20;34 33 4040 4046. Open 2. F Cardoso, S Kyriakides, S Ohno et al. Early breast cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2019 Aug 1;30 8 1194 1220. Open 3. Smith BD, Bellon JR, Blitzblau R et al. Radiation therapy for the whole breast: Executive summary of an American Society for Radiation Oncology ASTRO evidence-based guideline. Pract Radiat Oncol. 2018 May Jun;8 3 145 152. Open 4. Yash Vaidya, Pradeep Vaidya, Tanvi Vaidya. Ductal Carcinoma In Situ of the Breast. 2015 Apr;77 2 141 6.2015 Apr;77 2 141 6. Open 5. A Roca-Barcelo, G Vinas, H Pla et al. Mortality of women with ductal carcinoma in situ of the breast: a population-based study from the Girona province, Spain 1994 2013 . 2019 Jul;21 7 891 899.2019 Jul;21 7 891 899. Open 6. A Roca-Barcel , G Vi as, H Pla et al. Mortality of women with ductal carcinoma in situ of the breast: a population-based study from the Girona province, Spain 1994 2013 . Clin Transl Oncol. 2019 Jul;21 7 891 899. Open 7. Yash Vaidya, Pradeep Vaidya, and Tanvi Vaidya. Ductal Carcinoma In Situ of the Breast. Indian J Surg. 2015 Apr; 77 2 141 146. Open https://web.pathway.md/diseases/reclNi2rcyjrE9A7m 3/3