Assessing The Success Of A Strategy To Identify The Source Of Unknown Cancers

In some cases of cancer patients, the first presentation to a health care professional can be with a lymph node in the neck containing metastatic disease. The site of origin of cancer or the primary site is not always obvious, and further investigations are often needed to identify the source.

The standard workup of these patients involves taking a history, then an examination including flexible nasoendoscopy followed by conventional imaging (Computerised tomography (CT), Magnetic resonance imaging (MRI), and/or Positron Emission Tomography (PETCT). A Panendoscopy is carried out if imaging fails to detect the primary tumor; this is an examination of the upper aerodigestive tract with biopsies of the nasopharynx, hypopharynx, tonsillectomy, and targeted biopsies of the tongue base.

Despite all of these methods, the primary site may still not be identified. Transoral laser microsurgery (TLM) and Trans robotic surgery (TORS) of the tongue base are two new surgical techniques that are being increasingly used to help identify the site of the primary tumor. Both procedures involve removing the lymphatic tissue of the base of the tongue and preserving the underlying musculature, with the aim of identifying small cancer that cannot be seen during a clinical examination. In the literature, this is variably referred to as either lingual tonsillectomy or tongue base mucosectomy (TBM). We will use the latter to collectively describe these terms.

Our study is a systematic review and meta-analysis that aimed to assess the published literature on the use and efficacy of TBM in identifying the unknown primary site. We searched three main databases: MEDLINE, CINHAL, and EMBASE. We included studies that used a Transoral approach (TLM or TORS).

We identified 21 eligible studies with a total of 556 cases. 464 patients (83%) underwent TORS and 92 (17%) underwent TLM. Overall, Tongue base mucosectomy identified the primary tumor in the lingual tonsils in 58% of cases. However, this detection rate varied based on the diagnostic tests that had taken place prior to TBM. In patients who had negative clinical examination, negative CT/MRI imaging, negative PETCT, and negative EUA and biopsies, TBM identified the primary in the tongue base in 62% of cases. In 5 of the included studies, 90% or more of cases were positive for Human papillomavirus. In these cases, TBM successfully identified the primary site in 53% of cases. We also looked at the adverse events associated with the procedure. Our findings showed that hemorrhage was the most commonly reported adverse event in 4.9% of patients (13 studies).

Our study confirmed the high efficacy of TBM in identifying the primary site in cases of head and neck cancer, especially when other diagnostic methods have failed to identify the primary site.