Impact of Diagnostic Testing in Oncology

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Immunohistochemical staining and molecular testing have contributed tremendously to the evolution of diagnostic testing in the last 10 years, states F. Anthony Greco, MD. Using these tests allows for the type of cancer to be determined in 90% to 95% of patients. Prior to these advances, patients were treated with chemotherapy empirically, says Greco.

In the past, patients received a general cancer diagnosis and were given suitable treatment approaches, comments Suresh S. Ramalingam, MD. By contrast, today, treatment can be individualized based on the cancer type, the primary organ in which the cancer started, and the molecular abnormalities present in that particular disease.

Citing lung cancer as an example, Ramalingam notes that it is not enough to know that a patient has either small cell or non-small cell lung cancer (NSCLC). In a patient with NSCLC, it is important to know whether it is adenocarcinoma, squamous cell carcinoma, or large cell carcinoma. Additionally, key driver mutations, such as EGFR and ALK, should also be assessed.

To make a definitive diagnosis, adequate core tissue is needed for biopsy, says Ramalingam. In some cases, there may not be enough tissue for an adequate sample, or the tumor may be poorly differentiated, so that the markers and patterns are nonspecific. In these cases, gene expression panel testing, such as CancerTYPE ID, or CTID testing, may help identify where the cancer originated.