Does One Size Fit All? Is There a Standard Radiation Dose for Malignant Spinal Cord Compression
In this edition of the Journal of Supportive Oncology, Loblaw and Mitera have published a succinct review of trials of radiotherapy (RT) dose schedules for treating malignant spinal cord compression (MSCC). Treatment options for MSCC include surgery and RT, with the latter being the most commonly utilized option as the majority of patients are unfit to undergo surgery. This concise review of RT dose for spinal cord compression sheds light in an area where there are very few randomized controlled trials. Clinicians have historically favored multiple fraction regimens for treating patients with MSCC. The most common regimes are either 20 Gy in five fractions or 30 Gy in 10 fractions, with a single fraction of 8 Gy mainly reserved for patients with a poor performance status. Prospective studies suggest a different set of prognostic factors for deciding the dose of RT in these patients.
The Journal of Supportive Oncology
Volume 9, Issue 4, July-August 2011, Pages 127-128
doi:10.1016/j.suponc.2011.04.006 | Permissions & Reprints
Available online 2 July 2011.
Peer Viewpoint
Does One Size Fit All? Is There a Standard Radiation Dose for Malignant Spinal Cord Compression?
Ramachandran Venkitaraman MD, MRCP, FRCR
Commentary on “The Optimal Dose Fractionation Schema for Malignant Extradural Spinal Cord Compression" by D. Andrew Loblaw and Gunita Mitera (page 123).
Article Outline
In this edition of the Journal of Supportive Oncology, Loblaw and Mitera have published a succinct review of trials of radiotherapy (RT) dose schedules for treating malignant spinal cord compression (MSCC). Treatment options for MSCC include surgery and RT, with the latter being the most commonly utilized option as the majority of patients are unfit to undergo surgery. This concise review of RT dose for spinal cord compression sheds light in an area where there are very few randomized controlled trials. Clinicians have historically favored multiple fraction regimens for treating patients with MSCC. The most common regimes are either 20 Gy in five fractions or 30 Gy in 10 fractions, with a single fraction of 8 Gy mainly reserved for patients with a poor performance status. Prospective studies suggest a different set of prognostic factors for deciding the dose of RT in these patients.
The histology of the primary tumor is one of the important predictive factors for outcome. Patients with myeloma, breast, prostate, and thyroid malignancies have a favorable outcome. The survival rate for patients with tumors such as lung, melanoma, and sarcoma is generally dismal.[1] Mainly, primary tumors that are very sensitive to RT are lymphomas, myeloma, and seminomatous germ-cell tumors, as well as breast and prostate cancers. Gastrointestinal tract cancer, lung cancer, renal tumors, sarcomas, and gynecological tumors are considered to have poor radiosensitivity.
Randomized trials, especially in patients with unfavorable tumor histology, do not show any superiority for fractionated treatments compared to a single fraction of 8 Gy. [2] , [3] and [4] Single-fraction RT is advantageous in terms of time, cost, resources, and patient comfort. It should be considered as the standard dose for patients with extensive metastatic disease and a life expectancy of less than six months and for less radiosensitive primary tumors such as lung, melanoma, and sarcoma.
In patients with favorable histology, retrospective and nonrandomized evidence suggests a trend toward superiority of the higher fractionation schedules in terms of benefit in local control, with fewer in-field recurrences. [1] , [5] , [6] , [7] and [8] In the prospective SCORE-1 study, there was a statistically significant improved progression-free survival (72% at 12 months after long-course and 55% after short-course RT, P = 0.034) and local control (12-month local control rate, 77% after long-course and 61% after short-course RT, P = 0.032).5 With the ever-improving systemic treatment options for malignancies and the survival of these patients with metastatic disease showing an incremental increase with each decade, preventing recurrence of spinal cord compression becomes even more important. Long-course RT with doses of 30 Gy in 10 fractions offers no benefit compared to shorter regimens in terms of survival. However, long-course RT appears to improve local control, and there are fewer in-field recurrences, which would be an advantage in patients with favorable histology.[5] The longer schedule of RT, 30 Gy in 10 fractions, should also be considered in the postoperative setting, subject to recovery from the surgery. There is no practical advantage in offering treatments greater or longer than 30 Gy in 10 fractions in any patient subgroup.[9]
Similarly, in retrospective studies, for patients with limited metastases who are expected to live longer, survival is associated with tumor type, ambulatory status, slower development of motor deficits, and long-course RT.[10] The six factors demonstrated on multivariate analysis to be significant for survival outcome by Rades et al1 are primary tumor histology, visceral metastases, other extensive bone metastases, ambulatory status before RT, interval between tumor diagnosis and MSCC, and length of time in developing motor deficits. RT dose does not appear to affect the outcome in patients with low scores on these prognostic systems, while a longer-course RT may be effective in patients scoring highly.1
As recommended in the review article by Loblaw and Mitera, risk stratification of patients with MSCC is essential for deciding the dose of RT. A single fraction of 8 Gy is ideal for patients with poor prognostic factors. Randomized controlled trials of single vs. multifractionated treatments, similar to the SCORAD trial, determine the optimal dose-fractionation schedule of RT for MSCC with favorable prognostic factors.
