ELCC 2015 News: EGFR Mutation Detection Possible from Ultrasound-Guided Fine Needle Aspirates Taken from Patients with Lung Cancer

Additional invasive procedures may not be needed to determine EGFR mutation status

Samples taken by the currently approved method of ultrasound (US) guided fine needle aspiration (FNA) for detection of supraclavicular and cervical lymphadenopathy in patients with lung cancer could also be used for epidermal growth factor receptor (EGFR) mutation analysis, thereby decreasing or eliminating the need to take additional invasive samples.

These findings were presented by Prof. Amir Awwad, Department of Radiology, Nottingham University Hospitals NHS Trust, Queen's Medical Centre, Nottingham, UK on behalf of colleagues in a poster on during a Poster session at the European Lung Cancer Conference, held April 15-18, 2015 in Geneva, Switzerland.

EGFR mutation status is an important tool in guiding the clinical choice of targeted therapies for lung cancer. 

The authors pointed out that supraclavicular and cervical lymphadenopathy occurs in 15% to 30% of patients with lung cancer and, while US-guided FNA cytology serves as an effective diagnostic tool in small size lymph nodes and impalpable Positron Emission Tomography (PET) detected nodes, there was a paucity of data exist on whether this techniques can also provide information on EGFR mutation. They evaluated US-guided analysis of supraclavicular and cervical lymphadenopathy samples for the specificity and sensitivity in detection of EGFR mutations.

The team performed a retrospective data analysis from the electronic records of 306 patients with suspected lung cancer that had been referred for US-guided FNA of supraclavicular and cervical lymphadenopathy over a four-year period. Of these, 228 patients underwent the procedure and a cytological diagnosis was established in 171 (75%) patients for treatment decisions without further investigations.

Further investigative tests that included core lymph node biopsy, bronchial washings and lung biopsy were done in 57 patients; the diagnosis made by US-guided FNA was re-confirmed in 45 (75%) patients.

Positive cytology could be performed in lymph nodes ranging from 3 to 45 mm and the average lymph node size was 12.9 mm.

Ultrasound-guided supraclavicular lymph node fine-needle aspirates can provide reliable EGFR mutation testing with high sensitivity and specificity

EGFR testing was done in 34 of the 57 patients with adenocarcinoma. Four samples were positive for EGFR mutation, 25 were negative and 5 samples were insufficient for EGFR mutation analysis.

The investigators compared US guided FNA by statistical methods to a composite of all further tests used to identify EGFR mutations and found that US guided FNA had sensitivity of 76.9% (95% CI 63.2%, 87.5%) and specificity of 100% (95% CI 47.9%, 100%).

The positive predictive values of US guided FNA was 100% in comparison to all further tests, core lymph node biopsy, bronchial washings and lung biopsy, The negative predictive value of US guided FNA was 29.4%, 20%, 42.9% and 25% compared to all, further tests, core lymph node biopsy, bronchial washings and lung biopsy, respectively. The negative likelihood ration was 0.23, 0.18, 0.3 and 0.4, for US guided FNA compared to all, further tests, core lymph node biopsy, bronchial washings and lung biopsy. The positive likelihood ratio was not available for all parameters.

Patients reported no complication related to any of the procedures performed.

Conclusion

Based on results contained in this poster Prof. Awward stated that it may not be necessary for determination of EGFR mutation status to obtain additional samples by alternative methods such as bronchial washings and lung or core lymph node biopsy when US-guided FNA have already been taken from patients with lung cancer. 

The investigators concluded that, in most patients, US guided FNA provided reliable EGFR mutation status that was highly sensitive and specific. Furthermore, US guided FNA gave better positive predictive value information on EGFR mutation in comparison to the other techniques used in this study.

Reference

5P. Reliable EGFR mutation testing in ultrasound guided supraclavicular lymph node fine needle aspirates: A cohort study with diagnostic performance analysis