Discussion:
XP is a rare autosomal recessive disease with 100% penetrance. Patients have sensitivity to ultraviolet (UV) radiation, thereby increasing the risk of cutaneous tumours, such as squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and cutaneous melanoma (CM).1The most common cause of death in XP patients is skin cancer5
Normal individuals harbouring XPD polymorphisms are at increased risk for developing acute leukaemia. In a study by ElMahgoub IR et.al, which evaluated polymorphisms of xeroderma pigmentosum genes (XPC, XPD, and XPG) and susceptibility to acute leukaemia among a sample of Egyptian patients, homovariant for XPD had four fold increased risk of developing AML (OR = 4.4, P = 0.025) either alone or with variant genotypes of XPC and XPG.6
The published cases of XP with haematological malignancies are summarised in table 1. Most of the patients were adolescents, with the youngest being a 7 year old with B-ALL with MDS. Death due to leukaemia and treatment related toxicity were observed in all patients except for one.
Treatment of hematologic malignancies in patients with defective DNA repair pathways requires careful consideration.8Patients with XP generally tolerate diagnostic X-rays and radiotherapy.9 However, sensitivity to certain chemotherapies depends on the specific NER deficiency.10
Sumiyoshi et.al11, reported 2 cases of adults with XP, who were relatives, treated using cisplatin for papillary-predominant adenocarcinoma and squamous cell carcinoma of oesophagus. Both of them had enhanced adverse reactions and antitumor activity. The first patient developed diarrhoea, vomiting, transaminitis, hyperbilirubinemia, acute kidney injury (AKI) requiring haemodialysis and complete hearing loss. The second patient developed hearing impairment requiring hearing aid, AKI and severe myelosuppression, leading to death.
In contrast to these reports, our paediatric patient tolerated induction ALL chemotherapy relatively well. Even though there was transient derangement of liver function tests during induction, Pseudomonas sepsis and oral mucositis during protocol M and hyperbilirubinemia during maintenance, he remains disease free at 26 months from diagnosis.