High Dose Proton Therapy for Soft Tissue Sarcoma of Trunk Type of Session: Scientific Session

Reporter: J. Taylor Whaley, MD
The Abramson Cancer Center of the University of Pennsylvania
Ultima Vez Modificado: 21 de mayo del 2012

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Presenter: Hiroshi Fuji
Presenter's Institution: Shizuoka Cancer Center, Japan

Background

  • Soft tissue sarcomas are a group of tumors that originate from muscle, fat, and tendons. Soft tissue sarcomas are a rare group of cancers and encompass a group of 50 different types of tumors.
  • Overall, soft tissue sarcomas account for less than 1% of all adult cancers, with approximately 10,000 new cases annually.
  • The majority of soft tissue sarcomas are found in the extremities (about 50%); however, approximately 20% of soft tissues sarcoma are found in the retroperitoneal or trunk region.
  • Negative factors associated with poor outcomes for sarcomas include high grade histology, larger tumors, unresectability or positive margins, deep location, and older age.
  • Historically, patients able to undergo a complete resection are noted to have a 5-year overall survival of 70%; however, patients with a subtotal resection or unresectable disease have approximately a 30% rate of 5-year overall survival. Because of the poor outcomes associated with radiation to gross tumor, dose escalation is an area of active interest. Previous publications with photon-based radiation have shown improved outcomes with greater than 63 Gy.
  • Due to the large tumors and very high doses of radiation required to treat sarcomas in the trunk, proton therapy offers a therapeutic tool for dose escalation while minimizing treatment related toxicity.
  • The purpose of this study was to evaluate the role of high dose proton beam therapy for eradication of soft tissue sarcomas arising in the thorax and pelvis. The authors report their experience with patients treated with proton therapy at the Shizuoka Cancer Center in Japan.

Methods

  • From March 2004 to November 2009, 16 consecutive patients with primary soft tissue sarcoma localized to the trunk were treated with proton beam therapy.
  • Mean age was 66 years (Range, 20-84). Six females and 10 males were included in this analysis.
  • Six patients had truncal tumors and 10 patients had pelvic or abdominal tumors.
  • Histology included myxofibrosarcoma (5), leiomyosarcoma (3), spindle cell sarcoma (2), and other types of sarcoma (6).
  • Tumor size ranged from 20-2565 mL with a median of 493 mL. Eight patients (50%) had tumors greater than 600 mL.
  • All patients were treated with hypofractionated radiation for either part or entirety of treatment. Seven patients received combination photon and proton-based radiation.
  • Prescribed doses were 54-60 GyE in 2 cases, 61-70 GyE in 4 cases, and 71-84 GyE in 10 cases.
  • Concurrent chemotherapy was performed in 10 cases. Adjuvant chemotherapy was given in 14 cases.
  • Retrospective review of these 16 patients was done and clinical outcomes with rates of disease control are presented.

Results

  • With a median follow up of 24 months (Range, 7-60 months), overall survival and local progression free survival at 2 years was 67% and 70%, respectively.
  • Disease progression was observed in 8 cases with 5 patients progressing at the site of original tumor.
  • There was no apparent correlation between dose and recurrence.

2 year

3 year

5 year

Overall Survival

67%

57%

57%

Local Control

70%

45%

45%

Disease Free Survival

53%

35%

35%

  • Acute grade 3 radiation dermatitis occurred in 1 patient.
  • Delayed grade 3 GI bleeding occurred in 2 patients at 9-12 months.

Authors' conclusions

  • In patients with soft tissue sarcoma of the trunk, high-dose proton therapy offers an effective treatment with acceptable toxicity. Local control remains problematic and not different from historical controls.
  • Combination chemotherapy is feasible and may improve tumor control.
  • Further dose escalation may be warranted given poor local control observed here.
  • Further follow up is required to evaluate the delayed side effects of proton therapy.

Scientific/Clinical Implications

  • The authors present their initial experience with proton radiotherapy for soft tissue sarcomas of the trunk. The presentation is certainly a valuable contribution to the standing body of literature.
  • Soft tissue sarcomas of the trunk represent a rare tumor that requires aggressive treatment for an attempt at local control. Due to the small number of cases of soft tissue sarcoma diagnosed in the United States annually and the heterogeneity of the histology, prospective trials are difficult to perform. The majority of literature involves retrospective reports from single institutions.
  • Due to the large size and frequent unresectability of sarcomas in the trunk, proton therapy is a viable option for dose escalation. Proton therapy offers potential dosimetric advantages for cancers deep within the thorax, abdomen, and pelvis, and the acute toxicity appears to be acceptable. Due to the rapidly evolving techniques surrounding proton therapy, this very difficult and debilitating disease could be effectively treated with fewer side effects than previously seen.
  • Although surgical resection remains the mainstay of treatment for sarcomas, dose-escalated proton therapy may offer potential cure to patients with unresectable disease in the future.
  • Information on late effects and long term outcomes associated with this treatment will certainly contribute to the literature when longer follow-up permits analysis of quality of life and disease control following proton beam radiotherapy.

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