Main Session
Sep 28
PQA 04 - Breast Cancer, Patient Reported Outcomes/QoL/Survivorship, Functional Radiation Medicine, Hematologic Malignancies, Palliative Care, and International/Global Oncology

2703 - The Impact of Clinical and Dosimetric Factors on the Incidence of Radiation Induced Lung Injury (RILI) in Breast Cancer Patients Treated with Volumetric Arc Therapy (VMAT)

03:00pm - 04:00pm ET
Poster Hall - Exhibit Hall A
Screen: 7
POSTER

Presenter(s)

Rimoun Boutrus, MD, PhD Headshot
Rimoun Boutrus, MD, PhD - Bahrain Oncology Center, Muharraq, Muharraq

R. Boutrus1,2, A. A. AlHammadi1, S. Alkhlofi3, G. J. George Sr1, R. Alrowaiei1, A. Eid1, M. Sallam1, M. Bayomy4, and Z. Al Haddad1; 1Bahrain Oncology Center, Royal Medical Services, Muharraq, Bahrain, 2Radiation Oncology Department, National Cancer Institute, Cairo University, Cairo, Egypt, 3Bahrain Oncology Center, Muharraq, Bahrain, 4Hematology Oncology Department, Salmanya Medical Complex, Manama, Bahrain

Purpose/Objective(s):

The aim of the current study is to evaluate the incidence of RILI in breast cancer patients treated with VMAT technique and to investigate different clinical and dosimetric variables that contribute to its occurrence

Materials/Methods:

The medical records of 150 female patients with breast cancer, treated with adjuvant radiation therapy using VMAT technique in the period from January 1st, 2021, till December 31st, 2024, were reviewed and included in this analysis. All patients received whole breast/chest wall irradiation. Boost dose of 10 Gy was given to 80 (53%) patients. A separate supraclavicular field (SCF) was added in 54 (36%) patients. One patient received radiation to the internal mammary chain. Deep Inspiratory Breath Hold was used in 67 (44.7%) patients. Early and late RILI were recorded and graded according to the CTCAE v. 5.

Results:

Median follow up was 39 months (range, 3 - 52). Median age was 57.5 years (range, 29-79). The incidence of any RILI was 14 %, while the incidence of GII or higher RILI was 2.6%. The median ipsilateral lung volume was 1249 cc, (range, 377-2833). Median ipsilateral lung V5Gy was 61.4% (range, 15.4-79), V10Gy 31.4% (range, 10-75), and V20Gy 15.4% (range, 5.55-30.39). On univariate logistic regression analysis, factors that increased the odds of RILI were higher PTV D95% (OR 1.654, 95% CI 1.125-2.431, p 0.011), SCF volume ( OR 1.177, 95% CI1.155-2.998, p 0.037), prior lung disease (OR 4.101, 95% CI 1.086-15.492, p 0.036) and increased ipsilateral lung V20 Gy ( OR 1.384, 95% CI 1.186-1.995, p 0.04). On Multivariate analysis, the ipsilateral lung V20 Gy was the only factor the independently predicted RILI (OR 1.820, 95% CI 1.739-1.911, p 0.001).

Conclusion:

The incidence radiation induced lung injury is low in breast cancer patients treated with volumetric arc therapy. High dose lung volumes (V20Gy) are more important in predicting RILI. Respiratory disease records should be taken into account in radiation therapy planning