Patient Presentation:

A 74-year-old male was referred to our clinic following resection of a 9 cm myxofibrosarcoma spanning the chest wall and flank. The pathology was high-grade (FNCLCC Grade 3 of 3) with epithelioid features, Stage IIIA, cT2N0M0G3, s/p resection with close (<2mm), but negative margins. After discussion in our sarcoma multidisciplinary clinic and tumor board, including the director of orthopedic oncology, additional surgery was not advised. Instead, adjuvant post-operative radiation was advised to reduce the risk of recurrence.

Treatement:

After thorough review of his case and extensive discussion with the patient, we recommended treatment with proton therapy for this primary soft tissue sarcoma of the flank spanning the adjacent thorax, abdomen and pelvis, considering the high dose (2 Gy RBE x 31-33 daily treatment fractions = 62-66 Gy RBE) required to be delivered to better ensure local control and reduce the risk of local recurrence.

Proton beam therapy is an FDA-approved treatment modality that involves using focused beams of proton particles to treat malignancies. The primary advantage of proton treatment for sarcoma in this case is the precision of the proton beam and ability to better spare the adjacent organs at risk. The proton therapy fields can be designed to deliver dose directly to the tumor bed with significantly reduced entrance dose and essentially no exit dose, thus reducing the risk of damage to the surrounding health tissue and organs, specifically the lung, spine, spleen, bowel and other adjacent, normal tissues, as noted in the comparative treatment plan and dose volume histogram below (see Figure). Moreover, considering the scatter radiation dose from photon-based treatment, such as IMRT, proton beam therapy was the preferred option to potentially improve his long-term functional outcomes and reduce the risk of a secondary cancer. 

Outcome:

The patient tolerated the treatment very well with minimal impact. He experienced mild anticipated skin hyperpigmentation without any peeling or breakdown. This skin hyperpigmentation diminished over time several weeks after treatment. He did not have any other short term or long-term effects. He denied pain or loss of function. He was able to resume physical therapy after the proton therapy treatment to ensure maximal gain in function and to minimize long-term stiffness or fibrosis. The patient was able to resume his work as a security guard without significant disruption. At 18 months out of radiation, he remains without evidence of recurrence of his cancer.

Proton therapy provided lower cumulative doses to normal tissues and critical adjacent organs at risk, compared to photon-based external beam radiation. It was non-invasive, completely outpatient-based, extremely well tolerated, and had a near-negligible impact on patient energy level with minimal recovery necessary. Proton therapy provided the best chance for the patient to maintain excellent functional capacity and quality of life and reduce short- and long-term morbidity.

Figure:

Comparison of proton versus photon therapy for post-operative treatment of soft tissue sarcoma of the trunk and flank.

 

Proton	Photon

 

Proton	Photon