Validation and Added Clinical Value of Rapid On-site Diagnostics in Early Stage Lung Cancer Sampling With a Higher Harmonic Generation Microscope

The gold standard for diagnosing all suspected malignancies, such as lung cancer, involves pathological examination using light microscopy, supplemented with immunohistochemical techniques and molecular (tissue) diagnostics. The official assessment of this tissue typically occurs after the procedure in which the tissue was obtained, through histological analysis (tissue analysis) or cytological analysis (cell analysis obtained through aspiration). Only then can certainty be provided regarding whether the obtained tissue is qualitatively adequate and/or quantitatively sufficient to make a diagnosis.

To ensure that complex and/or invasive procedures are performed with the correct outcome measures, intraoperative tissue diagnostics would be beneficial. In addition to postoperative assessment, additional intra-procedural evaluation of material for qualitative and quantitative estimation ('rapid onsite evaluation' (ROSE) and 'frozen section examination') is often used for complex and/or invasive procedures. Rapid on-site evaluation of cytopathology is always present during navigational bronchoscopy procedures, while frozen section examination is used for surgical tissue resection (such as in lung cancer surgery, as well as in oncological ENT and oesophageal surgery, among other organ and malignancy suspicions).

Navigational Bronchoscopy For patients with (a suspicion of) early-stage lung cancer, navigational bronchoscopy is a labour-intensive, complex procedure that has now become the new standard of care for diagnosing abnormalities suspicious for lung cancer. An endoscope and a subsequent navigable catheter are used to navigate through the natural airways to the suspicious lesion and obtain a biopsy to make a diagnosis. Since these are often peripheral small lesions, it is crucial to obtain tissue with millimetre precision. During navigational bronchoscopy, the previously mentioned ROSE technique is routinely used to receive feedback during the procedure on whether the obtained tissue is suitable for making a diagnosis. Histological and/or cytological tissue is collected using small instruments during navigational bronchoscopy, such as a slide filled with cell material. The cytology analyst assesses within minutes whether the material is representative by colouring and examining it under the microscope. Representativity means that the material contains enough for performing final pathology diagnostics to explain the abnormality. Since navigational bronchoscopy involves only small biopsies and tissue from the tumour itself or surrounding tissue is not obtained with certainty under direct visualization (biopsies are taken under the guidance of X-ray fluoroscopy), multiple and extensive biopsies are performed. In current clinical practice, routinely more than ten biopsies are taken per patient. In practice, we observe under intraoperative imaging that we could accurately reach the lesion in more than 90% of cases. In later follow-up, it turns out that in about 10-15% of procedures, we still cannot provide a correct diagnosis after analysing the obtained material.

Surgery Similar to ROSE during navigational bronchoscopy, frozen section examination is also requested during surgical procedures when there is no diagnosis available at the start of the procedure or when clinically relevant lymph node stations affect the intervention. Tissue is taken, and an employee brings it to the pathology department. The progress of the surgical procedure is paused. The tissue is frozen on the pathology department to cut sections, which are then coloured and assessed by the pathologist. Due to these activities, this means that the surgeon typically waits for more than half an hour for a pathology result during the surgery.

This approach is customary in numerous surgical procedures, not only in lung surgery but also in procedures for patients with oesophageal cancer, head and neck cancer, and other solid tumours elsewhere in the body.