Research Note: Interpreting findings of a systematic review using GRADE methods

Recurrence in Oral Leukoplakia: A Systematic Review and Meta-analysis

The management of oral leukoplakia (OL) is challenging because of a high risk for recurrence and malignant transformation (MT), and recurrent OL is associated with a higher risk of MT than nonrecurrent OL. The present meta-analysis aimed to examine the association between OL recurrence and surgical techniques used for their management as well as their clinicopathological factors. Electronic searches were conducted in EMBASE, PubMed, Scopus, and Web of Science to retrieve studies reporting OL recurrence after surgery. The pooled proportion of OL recurrence after surgical excision was estimated. Subgroup analyses were conducted based on the surgical technique, data type, grades of epithelial dysplasia, anatomical subsites, clinical type and size of the lesion, surgical margin, and risk habits. Meta-regression analyses were conducted to identify the association between age, sex, and follow-up duration and OL recurrence. The risk of MT based on the recurrence status was also estimated. A network meta-analysis was performed to determine the surgical modality associated with the least OL recurrence. Eighty studies with a total of 7,614 samples and various surgical modalities (laser-based techniques, conventional scalpel surgery, cryosurgery, and photodynamic therapy) were included in the meta-analysis. A pooled proportion of recurrence of 22% was observed. Laser-based surgeries resulted in fewer OL recurrences than other surgical modalities, and the combination of laser excision and vaporization was identified to be the best treatment approach. OL in the retromolar area and multiple sites, nonhomogeneous OL, advanced age, female sex, inadequate surgical margin, retrospective data, and betel quid chewing habit were significantly associated with higher OL recurrence. Recurrent OL showed a 7.39 times higher risk of MT than nonrecurrent OL. These results suggest that the combination of laser excision and vaporization might reduce OL recurrence. Furthermore, OL in older patients, females, and nonhomogeneous OL need close monitoring after any surgical therapy.

The Role of Nicotinamide as Chemo-Preventive Agent in NMSCs: A Systematic Review and Meta-Analysis

BACKGROUND

Nicotinamide is the active form of vitamin B3 (niacin) obtained through endogenous synthesis, mainly through tryptophan metabolism and dietary supplements, fish, meats, grains, and dairy products. It participates in cellular energy metabolism and modulates multiple cellular survival and death pathways. Nicotinamide has been widely studied as a safe chemopreventive agent that reduces actinic keratosis (AKs) and non-melanoma skin cancers (NMSC).

METHODS

We used the Medline, EMBASE, PubMed, and Cochrane databases to search the concepts "nicotinamide", "chemoprevention", and "skin cancer" up to August 2023. Three independent authors screened titles and abstracts for intervention and study design before searching full texts for eligibility criteria. The primary outcome was the impact of oral nicotinamide on the incidence of NMSC in high-risk patients. We also conducted a systematic search to identify relevant epidemiological studies published evaluating dietary niacin intake and the risk of NMSC.

RESULTS

Two hundred and twenty-five studies were reviewed, and four met the inclusion criteria. There was no association between NAM consumption and risk for squamous cell carcinoma (SCC) (rate ratio (RR) 0.81, 95% CI 0.48-1.37; I2 = 0%), basal cell carcinoma (BCC) (RR 0.88, 95% CI 0.50-1.55; I2 = 63%), and NMSC (RR 0.82, 95% CI 0.61-1.12; I2 = 63%). Adverse events were rare and acceptable, allowing optimal compliance of patients to the treatment. We found only one article evaluating the association between niacin dietary intake and NMSC risk, supporting a potential beneficial role of niacin intake concerning SCC but not BCC or melanoma.

CONCLUSIONS

The present meta-analysis shows, by pooling immunocompetent and immunosuppressed patients, that there is insufficient evidence that oral nicotinamide therapy significantly reduces the number of keratinocyte cancers.