Cardiac sparing characteristics of internal mammary chain radiotherapy using deep inspiration breath hold for left-sided breast cancer

Abstract

BackgroundWhile breast radiotherapy typically includes regional nodal basins, the treatment of the internal mammary nodes (IMN) has been controversial due to concern for long-term cardiac toxicity. For high risk patients where IMN treatment is warranted, there is limited data with regards to the degree of heart sparing conferred by modern techniques. In this study, we sought to analyze the specific heart sparing metrics conferred by deep inspiration breath hold (DIBH) in the setting of IMN irradiation.MethodsFrom 2012 to 2015, 168 consecutive patients were treated with adjuvant left-sided radiotherapy using DIBH. Retrospective review identified 49 patients who received nodal irradiation, either to a supraclavicular field (SCF) and IMN (16), or to the SCF alone (33). Cardiac mean dose and dose volumes were calculated from free breathing (FB) and DIBH treatment plans, and compared by Wilcoxon signed-rank and Mann–Whitney U tests.ResultsDIBH achieved significant reductions in mean heart dose (p < 0.001) in both the IMN treated group from 6.73 Gy to 2.79 Gy (− 56.4%) and the IMN untreated group from 4.77 Gy to 1.55 Gy (− 63.7%). There was a 7.3% difference in relative reduction that was not statistically significant (p = 0.216). Relative reductions in heart dose volume measures were all significantly lower for IMN-irradiated patients (p ≤ 0.012), with the greatest deficits at V5 that gradually diminish with increasing dose (V25).ConclusionsThe relative heart sparing benefits of the DIBH technique are retained even with IMN inclusion. However, the addition of IMN irradiation is associated with an intrinsically greater heart dose, which translates to an estimated 9.2% proportional increase in the risk of a subsequent major coronary event. In the setting of effective cardiac sparing techniques, clinicians should take these considerations into account to guide when IMN treatment is warranted.

The effect of deep inspiration breath-hold technique on left anterior descending coronary artery and heart dose in left breast irradiation

“…Although the multileaf collimator could reduce cardiac dose, this study did not use it in order to assess the actual benefits of the DIBH technique over the FB technique. We found that the radiation doses to cardiac parameters were significantly reduced with the DIBH technique, similar to the results of previous A studies [9][10][11][18][19][20][21]. In the WB plans, the MHD was reduced from 5.38 Gy in FB to 2.95 Gy in DIBH (45.2% reduction) ( Table 1).…”

Can internal mammary lymph nodes irradiation bring survival benefits for breast cancer patients? A systematic review and meta-analysis of 12,705 patients in 12 studies

“…Therefore, under modern radiotherapy technology, the impact of IMNI on the occurrence of contralateral breast cancer needs more evidence to prove. At present, the wide application of deep inspiration breath hold technology has significantly reduced the dose of heart [ 31 ]. For complicated plans or patients with poor chest wall anatomy, new technologies such as VMAT and TOMO can also significantly reduce the cardiopulmonary dose of patients [ 32 , 33 ].…”

Mastectomy or Breast-Conserving Therapy for Early Breast Cancer in Real-Life Clinical Practice: Outcome Comparison of 7565 Cases

“…It is noteworthy, that the dose to axillary lymph node levels I and II usually is significantly lower than the prescribed dose and can range from 5% to 80% of the prescribed dose (mean value 48.7%). Even in patients receiving regional nodal irradiation of 50 Gray (Gy) to the supra-/infraclavicular lymph node levels (corresponding to levels IV, III and interpectoral lymph nodes), level I receives a reduced dose coverage of mean 41.3 Gy [26,27]. The potential influence of whole breast irradiation, especially in cases of pN+, needs further evaluation in randomized studies.…”