Detection of K-Ras mutations in tumour samples of patients with non-small cell lung cancer using PNA-mediated PCR clamping

Non-small cell lung cancers (NSCLC), in particular adenocarcinoma, are often mixed with normal cells. Therefore, low sensitivity of direct sequencing used for K-Ras mutation analysis could be inadequate in some cases. Our study focused on the possibility to increase the detection of K-Ras mutations in cases of low tumour cellularity. Besides direct sequencing, we used wild-type hybridisation probes and peptide-nucleic-acid (PNA)-mediated PCR clamping to detect mutations at codons 12 and 13, in 114 routine consecutive NSCLC frozen surgical tumours untreated by targeted drugs. The sensitivity of the analysis without or with PNA was 10 and 1% of tumour DNA, respectively. Direct sequencing revealed K-Ras mutations in 11 out of 114 tumours (10%). Using PNA-mediated PCR clamping, 10 additional cases of K-Ras mutations were detected (21 out of 114, 18%, P<0.005), among which five in samples with low tumour cellularity. In adenocarcinoma, K-Ras mutation frequency increased from 7 out of 55 (13%) by direct sequencing to 15 out of 55 (27%) by clamped-PCR (P<0.005). K-Ras mutations detected by these sensitive techniques lost its prognostic value. In conclusion, a rapid and sensitive PCR-clamping test avoiding macro or micro dissection could be proposed in routine analysis especially for NSCLC samples with low percentage of tumour cells such as bronchial biopsies or after neoadjuvant chemotherapy

Chemotherapy versus best supportive care in stage IV non-small cell lung cancer, non metastatic to the brain Quimioterapia versus melhor tratamento de suporte em câncer de pulmão estádio clínico IV não metastático para o sistema nervoso central

Stage IV non-small cell lung cancer is a fatal disease, with a median survival of 14 months. Systemic chemotherapy is the most common approach. However the impact in overall survival and quality of life still a controversy. OBJECTIVES: To determine differences in overall survival and quality of life among patients with stage IV non-small cell lung cancer non-metastatic to the brain treated with best supportive care versus systemic chemotherapy. PATIENTS: From February 1990 through December 1995, 78 eligible patients were admitted with the diagnosis of stage IV non-small cell lung cancer . Patients were divided in 2 groups: Group A (n=31 -- treated with best supportive care ), and Group B (n=47 -- treated with systemic chemotherapy). RESULTS: The median survival time was 23 weeks (range 5 -- 153 weeks) in Group A and 55 weeks (range 7.4 -- 213 weeks) in Group B (p=0.0018). In both groups, the incidence of admission for IV antibiotics and need of blood transfusions were similar. Patients receiving systemic chemotherapy were also stratified into those receiving mytomycin, vinblastin, and cisplatinum, n=25 and those receiving other combination regimens (platinum derivatives associated with other drugs, n=22). Patients receiving mytomycin, vinblastin, and cisplatinum, n=25 had a higher incidence of febrile neutropenia and had their cycles delayed for longer periods of time than the other group. These patients also had a shorter median survival time (51 versus 66 weeks, p=0.005). CONCLUSION: In patients with stage IV non-small cell lung cancer, non-metastatic to the brain, chemotherapy significantly increases survival compared with best supportive care.<br>O câncer de pulmão de células não pequenas em estádio IV é uma doença fatal, com uma sobrevida mediana de seis meses. Quimioterapia é a abordagem mais freqüente, apresentando um impacto na sobrevida controverso e questionável alteração na qualidade de vida. OBJETIVOS: Comparar o impacto na sobrevida global e na qualidade de vida em pacientes portadores de câncer de pulmão de células não pequenas, estádio IV, tratados com suporte clínico ou quimioterapia. PACIENTES: Entre fevereiro de 1990 e dezembro de 1995, 78 pacientes (pts) portadores de câncer de pulmão de células não pequenas estádio IV foram admitidos. Os pacientes foram divididos em dois grupos: grupo A (n=31 -- tratados com suporte clínico) e grupo B (n=47, tratados com quimioterapia). RESULTADOS: A sobrevida mediana no grupo tratado com suporte clínico foi de 23 semanas (variando de 5-153 semanas) e de 55 semanas no grupo tratado com quimioterapia (variando de 7,4 a 213 semanas), p= 0,0018 -- Qui-quadrada. Em ambos grupos, a incidência de internações hospitalares para a administração intravenosa de antibióticos e hemoderivados foi similar. Pacientes recebendo quimioterapia, foram estratificados entre àqueles que receberam mitomicina, vinblastina e cisplatina, n=25 e àqueles recebendo outros regimes (derivados de platina, associados à outras drogas, n= 22). Pacientes recebendo mitomicina, vinblastina e cisplatina, n=25 apresentaram uma incidência mais alta de neutropenia febril e tiveram atrasos mais longos entre os ciclos de quimioterapia, quando comparados aos pacientes do outro grupo. Pacientes recebendo mitomicina, vinblastina e cisplatina, n=25, também apresentaram uma pior sobrevida mediana (51 versus 66 semanas, p= 0,005 -- Qui-quadrado). CONCLUSÕES: Em pacientes com câncer de pulmão de células não pequenas, estádio IV, não metastático para os pulmões, o uso de quimioterapia aumenta a sobrevida de maneira estatisticamente significativa, quando comparado aos cuidados de suporte