Unresectable and chemoresistant conjunctival squamous cell carcinoma on xeroderma pigmentosum treated by salvage radiation therapy: A case report and a review of the literature

Xeroderma pigmentosum (XP) is a rare genetic disease, which vital prognosis is conditioned by the occurrence of cancers essentially of the skin and ocular surfaces, requiring an early and adapted management. Radiation therapy (RT) is a very effective modality in the therapeutic arsenal alongside surgery, but it remains underused as it is wrongly considered to be deleterious for these patients. In this article, we report the case of a 10‐years‐old girl with XP treated with external beam RT for a squamous cell carcinoma (SCC) of the right ocular conjunctiva. The clinical tolerance was excellent and we obtained a good tumoral response. Therefore, the place of RT in these patients could/should be reconsidered, especially since these suspicions have still not been confirmed.

DNA repair mechanisms in dividing and non-dividing cells

DNA damage created by endogenous or exogenous genotoxic agents can exist in multiple forms, and if allowed to persist, can promote genome instability and directly lead to various human diseases, particularly cancer, neurological abnormalities, immunodeficiency and premature aging. To avoid such deleterious outcomes, cells have evolved an array of DNA repair pathways, which carry out what is typically a multiple-step process to resolve specific DNA lesions and maintain genome integrity. To fully appreciate the biological contributions of the different DNA repair systems, one must keep in mind the cellular context within which they operate. For example, the human body is composed of non-dividing and dividing cell types, including, in the brain, neurons and glial cells. We describe herein the molecular mechanisms of the different DNA repair pathways, and review their roles in non-dividing and dividing cells, with an eye toward how these pathways may regulate the development of neurological disease.

Shining a light on xeroderma pigmentosum

Xeroderma pigmentosum (XP) is a rare, autosomal recessive disorder of DNA repair characterized by sun sensitivity and UV radiation-induced skin and mucous membrane cancers. Initially described in 1874 by Moriz Kaposi in Vienna, nearly 100 years later, James Cleaver in San Francisco reported defective DNA repair in XP cells. This eventually provided the basis for a mechanistic link between sun exposure, DNA damage, somatic mutations, and skin cancer. XP cells were found to have defects in seven of the proteins of the nucleotide excision repair pathway and in DNA polymerase η. XP cells are hypersensitive to killing by UV radiation, and XP cancers have characteristic "UV signature" mutations. Clinical studies at the National Institutes of Health found a nearly 10,000-fold increase in skin cancer in XP patients under the age of 20 years, demonstrating the substantial importance of DNA repair in cancer prevention in the general population. Approximately 25% of XP patients have progressive neurological degeneration with progressive loss of neurons, probably from DNA damage induced by oxidative metabolism, which kills nondividing cells in the nervous system. Interestingly, patients with another disorder, trichothiodystrophy, have defects in some of the same genes as XP, but they have primary developmental abnormalities without an increase in skin cancer.

DNA repair deficiency and neurological disease

The ability to respond to genotoxic stress is a prerequisite for the successful development of the nervous system. Mutations in various DNA repair factors can lead to human diseases that are characterized by pronounced neuropathology. In many of these syndromes the neurological component is among the most deleterious aspects of the disease. The nervous system poses a particular challenge in terms of clinical intervention, as the neuropathology associated with these diseases often arises during nervous system development and can be fully penetrant by childhood. Understanding how DNA repair deficiency affects the nervous system will provide a rational basis for therapies targeted at ameliorating the neurological problems in these syndromes.

Family history of cancer and risk of second malignancies in young cancer patients in Trieste, Italy

We carried out a cohort study in the Italian province of Trieste (2001 population, 242,000) to ascertain whether the risk of a subsequent primary cancer among 265 individuals diagnosed with a first malignancy at ages up to 25 years between 1971 and 1993 differed from that in the general population and to evaluate the effect of cancer family history, quantified by the family risk index (FRI), on the occurrence of second primaries. During the follow-up (median duration = 10 years; 25th-75th percentile = 2-16), 15 cohort members developed a second cancer vs. 1.60 expected for a standardized incidence ratio (SIR) of 9.4 (p < 0.0001). The overall SIR fell to 4.7 (p = 0.004) after excluding the 8 patients with well-known cancer-predisposing conditions (SIR = 300.0; p < 0.0001) and the 50 with a positive family history (FRI >/= 1.0) of malignant tumors (SIR = 20.0; p < 0.0001). Among 114 patients treated with radiotherapy and chemotherapy for their first neoplasms and not affected by predisposing disorders, 23 with a positive family history of cancer showed a 6.4-fold excess risk of second primaries (p = 0.008) compared with 91 with a negative history (FRI < 1.0). It is imperative that clinicians carefully and regularly evaluate cancer family history of young patients with malignancies. This would enable them to identify possible individual and familial features in patients at higher risk of multiple primaries and to adopt more suitable preventive and therapeutic measures.

Medulloblastoma: I. Clinical, diagnostic, and therapeutic overview

Medulloblastoma, the most common embryonal tumor of the central nervous system, affects both children and adults. It poses a significant therapeutic challenge in that age-dependent differences exist, not only in their pathobiology, but in the efficacy of chemotherapy and radiotherapy. This is particularly the case in very young children, whose still developing nervous system exhibits a low tolerance to radiotherapy. We review the epidemiology, clinical presentation, radiologic features, and current therapeutic concepts relative to this unique neoplasm. Efforts are made to highlight clinical controversies.