What is the cure rate using radiotherapy (radiation therapy) for a patient with recurrent sacrococcygeal chordoma?

Cure Rate of Radiotherapy for Recurrent Sacrococcygeal Chordoma

Cure is virtually impossible for recurrent sacrococcygeal chordoma, and radiotherapy alone offers extremely poor local control rates—approximately 14% (1 of 7 patients) achieved local control in the highest quality evidence available. 1

Critical Context: Prior Radiation Status Determines Feasibility

The feasibility and potential benefit of radiotherapy for recurrent sacrococcygeal chordoma depends entirely on whether the patient received prior radiation to the same anatomical area 2:

For Patients WITHOUT Prior Radiation to the Recurrence Site

Salvage radiotherapy with curative intent should be delivered using the same high-dose approach as primary treatment, requiring at least 74 GyE in conventional fractionation (1.8-2 GyE) for photon and proton therapy. 2 However, even with optimal dosing:

• Local control rates remain poor: In the definitive study by DeLaney et al., only 1 of 7 patients (14%) with recurrent sacral chordoma achieved local control after combined surgery and high-dose proton/photon radiation therapy, compared to 12 of 14 (86%) for primary tumors 1
• The mean follow-up for the single locally controlled recurrent case was only 2.9 years, suggesting even this success may be temporary 1
• Definitive radiotherapy alone (without surgery) is a reasonable alternative to surgery plus radiation, although neither approach is very effective 2

For Patients WITH Prior Radiation to the Same Area

Re-irradiation is only feasible if high-dose radiation can be delivered without exceeding organ-at-risk dose constraints, which is often impossible in the sacral region. 2 When re-irradiation cannot achieve adequate target coverage without exceeding dose limits, other treatment modalities are preferable 2

• The radiotherapist must reconstruct the previous radiation dose distribution accurately, but there is insufficient data to recommend an optimal re-irradiation dose and fractionation scheme 2, 3
• Carbon ion therapy may be considered for re-irradiation after initial low-LET treatment, as it may be more effective against radio-resistant clones selected by the first treatment 2
• Low-dose re-irradiation with palliative intent can be appropriate only if performed with negligible risk of toxicity 2

Evidence from Modern Particle Therapy Studies

Recent carbon ion and proton therapy studies provide additional context, though they primarily enrolled primary tumors:

• In a carbon ion study of 56 patients (15 with recurrent tumors), the 2-year and 3-year local control was 76% and 53% overall, but treatment for primary tumor resulted in significantly better local control than recurrent disease 4
• A randomized trial of 82 patients (13% recurrent) showed 2-year and 4-year local progression-free survival of 84% and 70%, but the study was not powered to analyze recurrent cases separately 5
• The definitive comparative study showed local control of 1/7 (14%) for recurrent vs. 12/14 (86%) for primary sacral chordomas treated with surgery and radiation 1

Critical Pitfalls to Avoid

• Do not assume radiotherapy alone offers meaningful cure rates for recurrent disease: The evidence consistently shows cure is virtually impossible, and the potential for cure is nil in most cases 2
• Do not proceed with re-irradiation without accurate reconstruction of previous dose distribution and verification that organ-at-risk constraints can be respected 2, 3
• Do not use low-dose radiation (<70 Gy) expecting disease control: Higher doses (≥70 Gy) may reduce local recurrence, but lower doses are associated with complications without disease control benefit 6

Recommended Approach for Recurrent Disease

The treatment goal should shift from cure to palliation, with careful selection of interventions that balance morbidity and quality of life 2:

• Salvage re-resection with curative intent should only be attempted in highly selected patients with isolated disease, long disease-free interval, and good performance status 2
• For patients with multifocal recurrent disease, cure is virtually impossible and aggressive curative-intent treatment should not be performed 2
• Palliative care should be incorporated from the beginning, including pain control, symptom management, and discussion of patient goals 2