Key result
In adjuvant radiotherapy for left-sided breast cancer, regional lymph node irradiation significantly increased the median mean heart dose to 4.6 Gy compared to 3.3 Gy without lymph node irradiation.
Why the study?
The heart and lungs are routinely exposed to incidental irradiation during adjuvant breast cancer radiotherapy, prompting an analysis of how patient and treatment characteristics affect heart and lung dose in left-sided breast radiotherapy.
Does the inclusion of lymph node radiotherapy or use of IMRT/VMAT increase heart and lung radiation doses in female patients receiving adjuvant radiotherapy for left-sided breast cancer?
Observational (n=332)
No
Does the inclusion of lymph node radiotherapy or use of IMRT/VMAT increase heart and lung radiation doses in female patients receiving adjuvant radiotherapy for left-sided breast cancer?
Absolute Event Rate: 4.6% vs 3.3%
p-value: p=<0.01
In left-sided breast cancer radiotherapy, the inclusion of lymph node irradiation significantly increases incidental radiation dose to the heart and lungs.
LN-RT raises heart and lung doses in left breast RT; leaves open optimal techniques to limit long-term cardiotoxicity.
The heart and lungs are routinely exposed to incidental irradiation during adjuvant radiotherapy (RT) of breast cancer. We analyzed the impact of patient and treatment characteristics on heart and lung dose in left-sided breast RT. We analyzed 332 female patients treated with left-sided breast RT between 2013 and 2018. Mean heart dose (MHD), left mean lung dose (MLD) and heart / lung V 20Gy were collected from treatment plans. Patients were stratified by RT technique (3D-conformal RT, 3DCRT; intensity-modulated RT, IMRT; volumetric modulated arc therapy, VMAT) and target volumes, including lymph node RT (LN-RT). Patient characteristics (body mass index (BMI), heart and lung volume) were assessed using correlation analyses. LN-RT was performed in 111 patients with increased MHD (median 4.6 vs. 3.3 Gy; p < .01), left MLD (14.8 vs. 7.7 Gy; p < .01) and left lung V 20Gy (30.0% vs. 14.4%; p < .01) compared to treatment without LN-RT. Internal mammary LN-RT further increased organ doses compared to RT involving only supraclavicular +/− axillary LN ( p < .01 for all values; MHD 6.9 vs. 4.2 Gy). In 221 patients treated without LN-RT, IMRT/VMAT was associated with higher left lung doses (MLD 9.1 vs. 7.4 Gy, p < .01; V 20Gy 18.8% vs. 14.0%, p < .01) compared to 3DCRT. A negative correlation between total lung volume and both MHD ( r = − 0.38; p < .01) and heart V 20Gy ( r = − 0.37; p < .01), as well as a weak positive correlation of BMI and MHD ( r = 0.27; p < .01) were observed. In adjuvant RT for left-sided breast cancer, LN-RT is associated with a marked increase in heart and lung doses, particularly with internal mammary LN-RT. Potential advantages of IMRT/VMAT for breast or chest wall RT need to be weighed against a moderately increased lung dose.
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Finazzi et al. (2019) conducted an observational in Left-sided breast cancer (n=332). Regional lymph node radiotherapy (LN-RT) vs. Radiotherapy without regional lymph node irradiation was evaluated on Mean heart dose (MHD) in Gy (p=<0.01). In adjuvant radiotherapy for left-sided breast cancer, regional lymph node irradiation significantly increased the median mean heart dose to 4.6 Gy compared to 3.3 Gy without lymph node irradiation.
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