Particle Therapy for Breast Cancer

Abstract

Particle therapy has received increasing attention in the treatment of breast cancer due to its unique physical properties that may enhance patient quality of life and reduce the late effects of therapy. In this review, we will examine the rationale for the use of proton and carbon therapy in the treatment of breast cancer and highlight their potential for sparing normal tissue injury. We will discuss the early dosimetric and clinical studies that have been pursued to date in this domain before focusing on the remaining open questions limiting the widespread adoption of particle therapy.

Keywords: breast cancer; carbon; particle therapy; protons.

Figure 1

A comparison of the dose deposition in tissue is shown between radiation therapy using six MV photons, protons, and carbon ions [4].

Figure 2

A comparison of the dose distribution comparing the same patient planned with 3D, VMAT, and pencil beam proton therapy.

Figure 3

(a) An example of extensive target volume coverage is demonstrated. Treatment with proton therapy to a dose of 64 GyE was delivered. The mean heart dose was 0.44 GyE, with a volume receiving 5 GyE of 2.8%. The volume of right lung receiving 20 GyE was 13.3%, and the total volume of lung receiving 20 GyE was less than 10%. (b) A case involving bilateral breast cancer is shown. The target was defined as the bilateral whole breast, and a boost was planned within the left breast. The patient suffered from baseline pulmonary hypertension and congenital heart block, and she was not able to perform deep inspiratory breath hold. Despite these features, only 0.4% of the total lung received at least 20 GyE, and the mean heart dose was 0.3 GyE.

Figure 4

A case of pre-operative reirradiation is shown, involving the necessity for extensive tissue coverage. Radiotherapy was delivered for the indication of gross residual disease, and proton therapy allowed for delivery of treatment with maximal cardiopulmonary sparing.