Comment

In the absence of randomised controlled studies, the comparative efficacy of local therapies in the treatment of KS cannot be assessed. High response rates have been described in uncontrolled case series for cryotherapy, photodynamic therapy and intralesional chemotherapy, but at the expense of troublesome local side-effects.

Is radiotherapy an effective local treatment for cutaneous Kaposi's sarcoma?

No systematic reviews were found. Two randomised trials in AIDS-related KS have compared different radiotherapy dose-fractionation schedules.20,21 There have also been many case series typically using total doses of radiotherapy ranging from 8 Gy to 40 Gy. However, the dose each lesion received in these series was individualised depending on both patient and lesion factors. Conclusions cannot be drawn from such non-randomised studies as to the optimum dose-fractionation schedule in AIDS-related KS.

No randomised studies of radiotherapy in classical KS, endemic KS or immunosuppression-related KS were found. Many retrospective case series of radiotherapy as a local therapy for classical KS have been reported suggesting it is a radiosensitive disease, but often criteria for assessment of response are not stated and vary between studies.

Efficacy AIDS-related KS

We found one randomised trial of radiotherapy in 71 cutaneous AIDS-associated KS lesions comparing three different dose-fractionation regimens: 8 Gy in a single fraction, 20 Gy in 10 fractions over 2 weeks and 40 Gy in 20 fractions over 4 weeks.20 Lesions were treated using 6 MeV electrons with 0-5 cm skin bolus allowing a 2 cm margin around palpable tumour. An objective response was defined as at least a 50% decrease in palpable tumour area, which was taken as the product of the perpendicular dimensions. Complete response was defined as resolution of all palpable tumour, with or without residual pigmentation. More complete responses were achieved with 40 Gy in 20 fractions (83%) and 20 Gy in 10 fractions (79%) than with an 8 Gy single fraction (50%). A greater proportion of complete responses were without residual purple pigmentation in the group that received 40 Gy (53%) than in the groups that received 20 Gy or 8 Gy (11% and 17%, respectively).20 The median time to treatment failure (defined as measurable growth in tumour area) for the 40 Gy, 20 Gy and 8 Gy groups were 43, 26 and 13 weeks, respectively.20

Another prospective randomised trial compared 8 Gy in a single fraction with 16 Gy in four fractions over 4 days for the treatment of cutaneous AIDS-related KS.21 A total of 596 lesions in 57 patients were treated, of which 172 lesions in 27 patients were treated in a randomised fashion. The method of randomisation was not reported. A total of 424 lesions in 49 patients were treated in a concurrent non-randomised prospective trial where the radiotherapy regimen was given according to patient preference. Lesions were treated using 75 or 100 kV superficial radiotherapy with a margin of 3-5 mm.

The overall response rate for the randomised and non-randomised lesions was 79% (465/590), which included complete responses and pigmented complete responses. The overall response rate for lesions treated with a single 8 Gy fraction was 78% (305/392), and 81% (160/198) for the lesions that received 16 Gy in four fractions. The overall response rates for the 172 lesions treated as part of the randomised trial were 71% (57/80) and 82% (75/92) for the 8 Gy and 16 Gy groups, respectively. The two response rates do not differ significantly (0-25>P>0-1). The response rate was highest in facial lesions. The response rates for the lesions treated non-randomly were 79% (248/313) for those that received 8 Gy and 80% (85/106) for those in the 16 Gy arm.21

A large retrospective case series of 643 patients with AIDS-related KS treated over a 10-year period (June 1986-December 1996) reported an objective response rate of 92% in 621 evaluable patients.22 The radiotherapy was delivered as a split course, with 20 Gy given in 2-5 Gy fractions over 2 weeks treating four times per week followed by 10 Gy in 1 week after a 2-week rest period. Extended cutaneous fields were treated with 4 MeV or 8 MeV electrons. Localised fields were treated with 45-100 KV superficial xrays.22

Another large series of AIDS-related KS lesions treated with radiotherapy retrospectively reviewed 375 lesions in 187 patients, of which 266 sites were cutaneous.23 The lesions were treated in a non-randomised fashion with total doses of 2-40 Gy in fractions of 1-5-8 Gy. Of the 266 cutaneous lesions, 111 received an 8 Gy single fraction and 155 received a more protracted fractionation regimen. In this study a response was defined as complete flattening of a lesion or a decrease in size to at least 50% of its pretreatment size, with reduced pigmentation. In total, 93% of the cutaneous lesions that received an 8 Gy single fraction responded, compared with 96% of the lesions that received a fractionated course of radiotherapy. The response or time to relapse did not differ between the two groups.23 Many smaller case series have used a variety of dose-fractionation schedules and have shown similarly high response rates of cutaneous KS to radiotherapy; however, criteria used to assess response vary.

Classical and endemic (African) Kaposi's sarcoma

We found no randomised studies of radiotherapy in endemic (African) or classical KS. A case series of 82 patients with classical KS treated with radiotherapy between 1972 and 1985 reported a complete response rate of more than 50% with doses ranging from 6-5 Gy in a single fraction to 35 Gy in 10 fractions.24 Long-term control was greater with doses of 27-5 Gy or more delivered in 10 fractions over a 2-week period.24 Brenner et al. reported a similar complete response rate for radiotherapy in classical KS of 58%.25 Another case series of 60 patients with classical KS treated with radiotherapy reported an overall response rate of 93%. In this study a variety of radiotherapy techniques were used, including megavoltage electrons, megavoltage photons, a combination of both, and total skin electron beam therapy.26

One retrospective case series of 28 men with endemic (African) KS treated with radiotherapy between 1978 and 1990 reported a complete response rate of 32% and a partial response rate of 54%, but the criteria used to assess response were not stated.27 The radiotherapy dose ranged from an 8-10 Gy single fraction to 14-24 Gy fractionated over 1-3 weeks using orthovoltage, cobalt60 or 6-8 MeV electrons.

0 0

Post a comment