The effect of age on the acquisition and selection of cancer driver mutations in sun-exposed normal skin

BACKGROUND

The accumulation of somatic mutations contributes to ageing and cancer. Sunlight is the principal aetiological factor associated with skin cancer development. However, genetic and phenotypic factors also contribute to skin cancer risk. This study aimed at exploring the role of photoaging, as well as other well-known epidemiological risk factors, in the accumulation of somatic mutations in cancer-free human epidermis.

MATERIAL AND METHODS

We deeply sequenced 46 genes in normal skin biopsies from 123 healthy donors, from which phenotypic data (including age, pigmentation-related genotype and phenotype) and sun exposure habits were collected. We determined the somatic mutational burden, mutational signatures, clonal selection and frequency of driver mutations in all samples.

RESULTS

Our results reveal an exponential accumulation of UV-related somatic mutations with age, matching skin cancer incidence. The increase of mutational burden is in turn modified by an individual's skin phototype. Somatic mutations preferentially accumulated in cutaneous squamous cell carcinoma cancer genes and clonally expanded with age, with distinct mutational processes underpinning different age groups. Our results suggest a loss of fidelity in transcription-coupled repair later in life.

CONCLUSION

Our findings reveal that ageing is not only associated with an exponential increase in the number of somatic mutations accumulated in normal epidermis, but also with selection and expansion of cancer-associated mutations. Aged, sun-exposed normal skin is thus an extended mosaic of multiple clones with driver mutations, poised for the acquisition of transforming events.

[Recurrent pyogenic granuloma]

The appearance of multiple satellite lesions is a rare complication of the treatment of a primary pyogenic granuloma lesion. We report 5 cases of recurrent pyogenic granuloma in patients aged between 4 and 31 years. The lesions resolved spontaneously after 1 to 9 months. Although the diagnosis and treatment of recurrent pyogenic granuloma can be problematic, this condition is benign and frequently self-limiting.

[Adverse cutaneous reactions to erlotinib]

INTRODUCTION

Erlotinib is an inhibitor of human epidermal growth factor approved for treating non-small cell lung cancer. The aim of this prospective observational study was to determine the prevalence of adverse cutaneous reactions caused by erlotinib and assess the management of such effects.

METHODS

Eleven patients with lung cancer and 1 with ovarian cancer received erlotinib at a dose of 150 mg/d. The prevalence, severity, and time course of the adverse cutaneous reactions were assessed.

RESULTS

The most frequent cutaneous reaction was acneiform eruption (10 cases). The patients were treated with topical erythromycin and clindamycin, or with doxycycline. Also reported were seborrheic dermatitis (5), paronychia (4), xerosis (3), mouth blisters (3), blepharitis (2), cheilitis (1), and fissures on the hands and feet (1). The first reactions to appear were seborrheic dermatitis (9.8 days until onset) and acneiform eruption (11.8 days), whereas the paronychia presented latest (65.3 days). One patient with acneiform eruption and another with paronychia suspended treatment until the lesions improved.

CONCLUSIONS

Erlotinib induces adverse effects in most patients treated. Acneiform eruption, seborrheic dermatitis, and paronychia are the most frequently reported reactions and can lead to temporary suspension of erlotinib administration.

[Analysis of lymphocyte populations in psoriatic plaques following inhibition of tumor necrosis factor alpha with etanercept]

INTRODUCTION

Psoriasis is a disease with a strong immunological component in which there is a predominant T helper 1 cell-mediated immune response. Etanercept, a receptor for tumor necrosis factor a that blocks its action, is a new drug with proven efficacy in the treatment of psoriasis.

OBJECTIVES

The primary objective of this study was to assess the histological response to etanercept by analyzing the lymphocyte populations in psoriatic plaques. The secondary objectives were to assess the clinical response to the drug using the Psoriasis Area and Severity Index (PASI) and to analyze the effect of etanercept on peripheral blood lymphocyte populations.

METHODS

Ten patients with plaque psoriasis and a PASI score greater than 10 were included in the study. A clinical assessment was performed in all patients along with a 4-mm skin punch biopsy of a plaque and analysis of peripheral blood lymphocyte populations at baseline and after 12 weeks of etanercept therapy at a dose of 50 mg per week.

RESULTS

There was a significant reduction in different lymphocyte populations in the plaques following treatment with etanercept. The mean (SD) number of CD4+ T lymphocytes per microscopic field decreased from 16.93 (8.13) at baseline to 6.51 (3.46) after treatment with etanercept (P < 007). CD8+ T lymphocytes also decreased from 17.73 (9.77) before treatment to 10.50 (9.4) after treatment (P < 005). An overall improvement in PASI score was also observed: 33.30 (10.71) at baseline versus 15.20 (13.28) following treatment (P < 008). Nine out of 10 patients showed improvement. No significant differences were observed in peripheral blood lymphocyte populations before and after treatment.

CONCLUSIONS

Etanercept leads to clinical improvement of psoriasis and reduces inflammatory infiltration of the lesions without affecting peripheral blood lymphocyte populations.

Treatment of psoriasis with adalimumab

BACKGROUND

Adalimumab is an anti-tumour necrosis factor agent of use in psoriatic arthritis.

AIM

The objective of this study was to assess the efficacy and safety of adalimumab in patients with plaque psoriasis unresponsive to previous therapies.

METHODS

We present nine patients with psoriasis and psoriatic arthropathy treated with adalimumab, including a woman with a history of breast cancer and a man with hepatitis C virus-related liver disease.

RESULTS

After 12 weeks, 66.6%, 55.5% and 11.1% of the patients showed a Psoriasis Assessment and Severity Index response of 50%, 75% and 90%, respectively. After 20 weeks, these levels had increased to 75%, 62.5% and 37.5%, respectively. After 12 weeks, the Psoriasis Global Assessment (PGA) score was clear or almost clear in 33.3% of the patients. By week 20, this clearance rate had almost doubled (62.5%). In two patients, the treatment was prolonged for 52 weeks, with a sustained response. One patient presented nonspecific colitis and died as a result of in-hospital pneumonia; any implication of adalimumab in the death is not clear. No other serious adverse effects were observed.

CONCLUSION

In this series adalimumab was found to be effective for psoriasis refractory to other treatments including infliximab and etanercept.

[Atypical pigmented penile macules]

Two patients with pigmented lesions of the penis are described. The lesions consisted of asymptomatic, multifocal, irregular macules, with variegated pigmentation. The main differential diagnostic problem was with mucocutaneous melanoma. Histologic examination of the lesions showed basal layer hyperpigmentation. No cytologic atypia of melanocytes was detectable. The diagnosis in both cases was melanotic macules. Because of their atypical clinical appearance, genital melanotic macules are often misinterpreted as mucocutaneous melanoma. However histopathologic study solves the problem because genital melanotic macules show no melanocytic proliferation nor melanocytic atypia.