ESTRO 2024 - Abstract Book

S625

Clinical - Breast

ESTRO 2024

PubMed, Scopus, and ISI Web of Science databases were searched for cohort studies related to secondary cancer after radiotherapy for breast cancer. Studies that assessed the relative risk (RR) of secondary malignancies comparing breast cancer patients with and without radiation were selected.

Results:

26 studies, including 3,734,933 breast cancer patients, were included. After at least 5 years, radiotherapy significantly increased the risk of all secondary cancers (RR: 1.26; 95% CI: 1.18, 1.35). Radiation was associated with secondary cancers of the contralateral breast (RR: 1.11; 95% CI: 1.04, 1.18), the lung (RR: 1.29; 95% CI: 1.17, 1.42), the esophagus (RR: 1.67; 95% CI: 1.14, 2.46), and sarcoma (RR: 2.01; 95% CI: 1.50, 2.69). Over a 10-year period radiation therapy for breast cancer was linked to an increased risk of secondary cancers (RR: 1.26; 95% CI: 1.20, 1.33), secondary cancers of the contralateral breast (RR: 1.33; 95% CI: 1.11, 1.60), the lung (RR: 1.43; 95% CI: 1.13, 1.81), the esophagus (RR: 1.61; 95% CI: 1.08, 2.39), as well as out of radiation field cancers including all hematologic malignancies (RR: 1.37; 95% CI: 1.15, 1.63), leukemia (RR: 1.52; 95% CI: 1.20, 1.93), genitourinary system (RR: 1.26; 95% CI: 1.09, 1.45), and melanoma (RR: 1.48; 95% CI 1.07, 2.04). Also, after 15 years of follow-up radiotherapy increased the risk of all secondary cancers (RR: 1.45; 95% CI: 1.16, 1.81), secondary lung carcinoma (RR: 1.52 95% CI: 1.23, 1.89), and secondary sarcomas (RR: 2.35; 95% CI: 1.43, 3.87).

Conclusion:

Radiotherapy is still an important aspect of breast cancer treatment, and its benefits in local tumor control and overall survival considerably outweigh the likelihood of secondary malignancies 10 to 15 years following treatment. Thus, optimizing breast cancer treatment requires developing radiotherapy techniques that minimize radiation exposure in adjacent tissue without reducing the dose to the affected breast.

Keywords: breast cancer, secondary cancer, radiotherapy.

References:

1. Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D. Global cancer statistics. CA: a cancer journal for clinicians. 2011;61(2):69-90.

2. Fisher B, Anderson S, Bryant J, Margolese RG, Deutsch M, Fisher ER, et al. Twenty-year follow-up of a randomized trial comparing total mastectomy, lumpectomy, and lumpectomy plus irradiation for the treatment of invasive breast cancer. New England Journal of Medicine. 2002;347(16):1233-41. 3. Veronesi U, Marubini E, Mariani L, Galimberti V, Luini A, Veronesi P, et al. Radiotherapy after breast conserving surgery in small breast carcinoma: long-term results of a randomized trial. Annals of Oncology. 2001;12(7):997-1003. 4. Liljegren Ga, Holmberg L, Bergh J, Lindgren A, Tabar L, Nordgren H, et al. 10-Year results after sector resection with or without postoperative radiotherapy for stage I breast cancer: a randomized trial. Journal of Clinical Oncology. 1999;17(8):2326-.