Adjuvant PSK immunotherapy in patients with carcinoma of the nasopharynx

A controlled study using adjuvant PSK immunotherapy in patients with nasopharyngeal carcinoma was initiated with the aim of improving survival by enhancing the host immune system against tumour cells. A total of 38 patients were randomly selected, all of whom had previously received radiotherapy with or without chemotherapy. Eight patients in the PSK immunotherapy group (n = 21) developed local recurrence, three of whom later died due to distant metastasis. In the control group (n = 17) three patients developed local recurrence while six patients developed distant metastasis. All of these six patients later died due to disease progression. It seems that PSK exerts its antitumour effect systemically; the risk of distant metastasis occurring is decreased, but it is apparently ineffective in improving local disease control. The estimated median survival time of the PSK-treated group compared with the control was significantly increased (35 months versus 25 months, P = 0.043). The 5-year survival rate was also significantly better in the PSK immunotherapy group (28% versus 15%, P = 0.043). It is concluded that PSK deserves careful consideration as an important immunotherapeutic agent in the management of nasopharyngeal carcinoma.