Introduction: Breast cancer (BC) is the most frequent and lethal chronic non-communicable disease in women, and available information on the impact that the different treatments for BC have on the respiratory system is controversial. Objective: To determine the effect of concurrent chemotherapy and radiotherapy on lung volumes in a group of women with BC living in Talca, Chile. Material and methods: Case-control study. The sample (n=22) was divided into two groups: control (n=11) and BC (n=11). A whole body plethysmography test was used to measure participants’ forced vital capacity, lung volumes, and airway resistance. The Shapiro-Wilks test was used to determine the normality of data, and, according to the result of this test, the Student’s t test or the Mann-Whitney U test were used. A significance level of p<0.05 was considered. Results: Ventilatory flows showed no significant differences between both groups, while lung volumes in the BC group experienced a significant decrease in the inspiratory capacity (IC) and residual volume (RV) variables (p<0.05). Conclusion: Compared to the CG, the women with BC who received concurrent chemotherapy and radiotherapy experienced a reduction of their IC and RV, which could affect their quality of life.