Adding High-Dose Radiation to Surgery Confers Survival Benefit in Patients With Chordoma

Chordoma, a rare primary tumor of the axial skeleton, can be locally controlled with en bloc resection. However, studies with more than four years of follow-up show high rates of disease recurrence despite negative surgical margins.

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A potential explanation comes from a study published in Annals of Surgical Oncology, which uncovered a relationship between local recurrence and micro-skip metastases in healthy tissues surrounding the tumor. Fortunately, proton and photon therapies can deliver tumoricidal doses while sparing adjacent healthy tissues.

A retrospective study at Massachusetts General Hospital, reported in The Spine Journal, showed that adding these newer therapies to surgical excision of chordoma has survival and disease control benefits. The authors are Daniel G. Tobert, MD, an attending surgeon in the Orthopaedic Spine Center, Joseph H. Schwab, MD, MS, director of spine oncology at Mass General and co-director of the Center for Chordoma Care at Mass General Cancer Center, and colleagues.

Methods

The research team studied 76 patients who underwent a first surgery for non-metastatic chordoma of the sacrum or mobile spine between 1990 and 2016. Patients living with less than five years of follow-up were excluded.

For chordoma, Mass General now typically administers a total dose of 70.2 Gy photon and/or proton therapy, split into 50.4 Gy neoadjuvant and 19.8 Gy adjuvant doses. 45 patients completed the planned dose (≥70 Gy) and 31 received <70 Gy.

Outcomes

Survival and disease control were significantly better for radiation completers regardless of surgical margin status:

• Five-year overall survival was better for patients who completed >70Gy radiation than those who didn't (82% vs. 63%; HR for death, 0.28; P=0.001)
• Five-year local recurrence–free survival was greater for patients who received >70Gy of radiation (93% vs. 78%; HR for recurrence, 0.23; P=0.017)

Multivariable Analysis

After adjustment for margin status and subtype of radiation therapy (proton, photon, or combined), overall survival was better when >70Gy of radiation was administered (HR, 0.39; P=0.046).

After adjustment for the radiation subtype, the local recurrence–free interval was no longer significantly different between patients who received ≥70 Gy and those who received <70 Gy. This suggests the radiation delivery modality influences the chance of local recurrence, a possibility that warrants more research.

Conclusions

This study was the first to examine survival and disease control in chordoma with a minimum follow-up of five years for each participant. The combination of surgical excision and radiation to 70 Gy appears to compensate for the risk of recurrence from microscopic residual disease, resulting in a survival benefit.

These findings support previous recommendations that chordoma should be treated at experienced centers with multidisciplinary teams and the latest radiation therapy techniques.

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