BRAF mutations rare in Japanese NSCLC patients

Research in a Japanese cohort of patients with non-small-cell lung cancer (NSCLC) indicates that the frequency of BRAF mutations is low and their presence has limited prognostic significance.

Among 2001 patients with surgically resected NSCLC, BRAF mutations were detected in just 26 (1.3%), report study authors Koji Tsuta (National Cancer Center Hospital, Tokyo) and colleagues.

“These incidence rates were lower than those reported in Caucasian populations (~3%),” the researchers note in the Annals of Oncology.

“The relative paucity of BRAF mutations in the Asian population may be related to ethnic differences and the high frequency of EGFR mutations in Asian women with lung adenocarcinoma,” they suggest.

There were 13 mutation genotypes detected, including V600E in 30.8% of cases, G469A in 23.1%, and K601E in 15.4%. There were also four patients with genotypes not previously reported in lung cancer: G464E, G596R, A598T, and G606R.

After a median follow-up of 61 months, 18 (69.2%) of the 26 patients with BRAF mutations were still alive, and there was no significant difference in overall survival between these patients and those with wild-type BRAF. There was also no significant difference in overall survival between patients with V600E and non-V600E mutation genotypes compared with patients with wild-type BRAF.

And, in contrast to previous research, the team found that patients with BRAF mutations had relatively low-stage disease.

However, they note: “The small number of BRAF mutation cases in our study precluded the drawing of definitive conclusions concerning the prognostic significance of BRAF mutations in NSCLC.”

Overall, BRAF mutations were present in an equal number of men and women, with an average age of 64 years, of whom 54% were current or former smokers. Twenty-five tumors were adenocarcinomas and one was squamous cell carcinoma.

Noting that the prognostic significance of BRAF mutations appears to be influenced by disease site, Tsuta et al conclude that “[f]urther multicenter studies with larger patient populations are necessary to establish the role of BRAF mutations in NSCLC prognosis.”

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