Hong Kong Dermatology & Venereology Bulletin

Volume 12 Number 2, Summer 2004

Radiation-recall dermatitis associated with cytotoxic chemotherapy

W Yeo 楊明明

Radiation-recall dermatitis is a well-recognised phenomenon of an acute inflammatory toxicity that occurs in a previously quiescent radiation field with subsequent cytotoxic chemotherapy administration. It may occur from days to weeks, and sometimes years after the radiation therapy. The precise mechanism is unknown. One hypothesis suggests that the initial radiation therapy leads to a depletion of tissue stem cells within the irradiated field and that subsequent cytotoxic chemotherapy exposure causes a 'remembered' reaction among the remaining surviving cells. An alternative proposition suggests that radiation induces heritable mutations within surviving cells which then produce a subgroup of defective stem cells that are unable to tolerate the second insult of chemotherapy. Treatment is mainly supportive and most of the lesions will heal spontaneously. Some reports have noted that radiation recall dermatitis recurred with subsequent continual administration of the same chemotherapeutic agent, however such experience is non-universal. Preventative measures that have been employed to avoid recurrence of the condition include subsequent cytotoxic dose modification, prophylactic steroid coverage, and discontinuation of the implicated cytotoxic. (H.K. Dermatol. Venereol. Bull. (2004) 12, 71-77)

放射線回應性皮炎是為人熟知的現象。在過往曾經接受放療的無症狀區域,於化療後即出現急性炎症反應。它可於放療後數天,數週甚至數年出現。其確切的發病機制尚未明瞭。其中一個假設是,早期的放射治療令組織中的幹細胞減少,其後的化療則令餘下的幹細胞產生 "回憶反應" 。另一個假設是,早期的放療令餘下存活的細胞產生可遺傳的突變缺陷,而這些帶缺陷的幹細胞群落不能耐受其後的化療。此症主要用支持療法處理,皮損通常自行痊癒。病例報告中也有些放射線回應性皮炎再接受相同化療藥物後復發,但這並非會必然發生。預防措施包括:調整化療劑量,並用皮質激素以及停用懷疑致病的化療藥。

Keywords : Cytotoxic chemotherapy, radiation-recall dermatitis


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