Shades of gray: a personal view of palliation by radiotherapy

A role for radiotherapy in neuropathic bone pain: preliminary response rates from a prospective trial (Trans-tasman radiation oncology group, TROG 96.05)

PURPOSE

Radiotherapy (RT) has a proven role in palliation of pain from bone metastases with numerous randomized trials obtaining response rates (RRs) of typically 70-80% regardless of the fractionation employed. However RT for neuropathic bone pain (NBP), i.e., pain with a radiating cutaneous component due to compression/irritation of nerves by tumor has not previously been studied, and its role is thus uncertain.

METHODS AND MATERIALS

In February 1996, the Trans-Tasman Radiation Oncology Group (TROG) initiated a multicenter randomized trial comparing a single 8 Gy fraction with 20 Gy in 5 fractions for NBP with an accrual target of 270. Formal interim analyses were planned at 90 and 180 patients. The 90th patient was accrued in June 1998, and data from the first interim analysis with both arms combined form the basis of this report.

RESULTS

Forty-four patients were randomized to a single 8 Gy, 46 to 20 Gy in 5 fractions. The commonest primary sites were prostate (34%), lung (28%) and breast (10%). Median age was 68 years (range 37-89). The index site was spine (86%), rib (13%), base of skull (1%). On an intention-to-treat basis, the overall RR was 53/90 = 59% (95% CI = 48-69%), with 27% achieving a complete response and 32% a partial response. The overall RR for eligible patients was 49/81 = 60% (95% CI = 49-71%) with 27% and 33% achieving complete and partial responses respectively. Estimated median time to treatment failure was 3.2 months (95% CI = 2.1-5.1 months), with estimated median survival of 5.1 months (95% CI = 4.2-7.2 months). To date, six spinal cord/cauda equina compressions and four new or progressive pathological fractures have been detected at the index site after randomization, although one cord compression occurred before radiotherapy was planned to commence. In February 1999, the Independent Data Monitoring Committee strongly recommended continuation of the trial.

CONCLUSION

Although these results are preliminary, it seems clear that there is indeed a role for RT in the treatment of NBP. Analysis of outcome by treatment arm awaits completion of the randomized trial.

Patterns of fractionation for palliation of bone metastases

The patterns of fractionation used to treat bone metastases in a single centre in two time periods were determined. Clinical audit was carried out, for two periods of 6 months each, in 1988 and 1993. Data recorded included patient, tumour and treatment variables. Palliation of bone metastases represented 40% and 44% of palliative treatment courses, and 20% and 21% of total treatment courses, respectively, in both time periods. Shorter treatment schedules were used in 1993 compared to 1988, with mean fraction numbers of 6.4 versus 8.5, respectively (P < 0.001). This reduction in fraction numbers occurred for the common primary tumour sites. In 1993, the mean numbers of fractions used were related to the primary tumour site (7.8 fractions for breast, 5.0 for lung, 6.7 for melanoma, 6.4 for other primary sites, P = 0.05), the treatment site (7.3 fractions for weight-bearing bones, 4.0 for non-weight-bearing bones, P < 0.001) and patient address (6.0 fractions for city postcode vs 7.8 for country postcode, P = 0.02). Treating radiation oncologist (5.7-7.8 mean fractions, P = 0.06) and patient age (P = 0.56) were not significant factors for the number of fractions used. It is likely that there were multiple causes for a reduction in the number of fractions used to treat bone metastases, including the results of clinical trials and increasing pressure to optimize the use of scarce resources. However, patients who may have a better prognosis (breast primary) and those with metastases in weight-bearing bones continued to receive longer treatment schedules.