Breast cancer
Improved heart, lung and target dose with deep inspiration breath hold in a large clinical series of breast cancer patients

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Abstract

Background and purpose

This study aims at evaluating the effect of deep-inspiration breath hold (DIBH) on target coverage and dose to organs at risk in a large series of breast cancer patients.

Materials and methods

Clinical dose plans for 319 breast cancer patients were evaluated: 144 left-sided patients treated with DIBH and 175 free-breathing (FB) patients (83 left-sided and 92 right-sided). All patients received whole breast irradiation with tangential fields, based on a forward-planned intensity-modulated radiation therapy (IMRT) technique. Dose to heart, ipsi-lateral lung and ipsi-lateral breast were assessed and median values compared between patient groups.

Results

Comparing group median values, DIBH plans show large reductions of dose to the heart compared with left-sided FB plans; V20Gy (relative volume receiving ⩾20 Gy) for the heart is reduced from 7.8% to 2.3% (−70%, p < 0.0001), V40Gy from 3.4% to 0.3% (−91%, p < 0.0001) and mean dose from 5.2 to 2.7 Gy (−48%, p < 0.0001). Lung dose also shows a small reduction in V20Gy (p < 0.04), while median target coverage is slightly improved (p = 0.0002).

Conclusions

In a large series of clinical patients we find that implementation of DIBH in daily clinical practice results in reduced irradiation of heart and lung, without compromising target coverage.

Section snippets

Methods and materials

DIBH is part of the standard RT treatment for post-operative left-sided breast cancer patients in our department. It was introduced in two steps: from September 2010 for patients aged 60 years or less, and from February 2011 onwards DIBH has been the treatment of choice for all left-sided breast cancer patients.

The present study is based on a retrospective collection of dose volume histograms from the first 144 patients treated with DIBH in our clinic during the period from September 2010 to

Results

Main characteristics of the three patient groups can be found in Table 1. In total, 319 patients were included in the analysis, of which 144 were DIBH patients. Left sided breast cancer patients unable to comply with the requirements for DIBH were noted, but not included in the analysis of dose plan metrics; details of this group (20 patients) can be found in Table 2. The two main causes for non-compliance were inability to use the mouthpiece of the ABC equipment and psychological reasons.

The

Discussion

The benefits of post-operative RT for breast cancer patients, in terms of reduced risk of recurrence, have been clearly demonstrated, but concurrent heart irradiation leads to an increased risk of heart disease. At the moment, the dose–response relationship for radiation-induced heart disease remains uncertain [3], and thus the best approach seems to be to avoid direct irradiation of the heart altogether [16]. This, on the other hand, will often lead to lower target coverage for left-sided

Conclusion

From a retrospective analysis of dose plans from 144 left-sided breast cancer patients treated with DIBH we have found that, compared to free-breathing patients, there is a large reduction in heart dose and a smaller reduction in lung dose. This decrease in dose to organs at risk does not come at the cost of decreased target coverage, as we find that median PTV coverage is slightly improved and especially large compromises (with PTV coverage of <95%) are significantly reduced from 17% down to

Conflicts of interest

The authors report no conflicts of interest.

Acknowledgements

A.L.A. is supported by the Region of Southern Denmark and by CIRRO – The Lundbeck Foundation Center for Interventional Research in Radiation Oncology and The Danish Council for Strategic Research. The authors gratefully acknowledge the fruitful discussions with Martin Berg and Ivan R. Vogelius in the preparation of this manuscript.

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