The quest for a cure for cancer has spawned hundreds of research focuses. In recent years, with promising treatment results from targeted therapies, a great deal of attention has been paid to identifying types of cancers. As medicine continues to make significant strides in this area, pathology’s role is even more critical as the volume of knowledge grows.
One of the key care functions of anatomic pathology is the diagnosis of cancer. As the physicians that definitively diagnose all cancers, pathologists play a pivotal role in the fight against rising cancer rates. For over 100 years, when a patient presents with a tumor, a surgeon removes a sample which is then processed onto a glass slide for a pathologist to review.
The pathologist looks for patterns in size and shape to match against the characteristics of known cancer types. This methodology has served healthcare well for some time, but we now know that tumors are expressions of cancer rather than the cause.
Decades of genetics research have revealed that cancer is caused by a mutation in an individual’s cellular DNA. Mutations typically occur during the sometimes imperfect process of copying DNA during cellular replication or as a result of some external force, like radiation, that damages DNA. In most cases, these mutations are relatively harmless, causing the cell to die or triggering the immune system to kill it. Certain mutations, however, result in the cell functioning but with irregularity. These cells are cancer. When they continue to multiply, they form tumors which in turn damage tissue around them and can cause essential bodily functions to fail.
This development in our understanding of cancer has led to molecular testing. With these tests, we can potentially identify the existence of specific mutations in the DNA sequence of cancerous cells. Armed with molecular testing, pathologists can use the binary positive or negative indication of the existence of a mutation to help improve their diagnoses. The goal is to identify the various “molecular signatures” that uniquely determine each cancer type.
At present, several molecular signatures for cancers are known and ongoing research continues to identify more. Also necessary is the identification of actionable treatments that correlate with each molecular signature, meaning that pathologists—and care teams as a whole—can gain valuable insights into a patient’s prognosis or potentially define a more optimal course of treatment. As researchers pursue research in molecular testing, we continue to discover new subcategories of cancer types. This creates more opportunities for personalized medicine, especially when these subcategories are impossible to distinguish visually through traditional pathology. Molecular testing enables those subcategories to be distinctly identified and diagnosed with the relevant targeted therapies applied.
In clinical applications, molecular testing is another tool at the pathologist’s disposal, working alongside the pathologist’s expertise and ability to synthesize a patient’s medical history while also evaluating individual tumor samples. In this sense, the pathologist is the integrator of an increasingly complex body of diagnostic knowledge, of which molecular testing is a part. The pathologist is charged with keeping abreast of what tests to order, looking at the whole of the patient picture while evaluating samples, and helping consult with oncologists on the actionable outcomes of these tests.
This growth in diagnostic information is both an opportunity for pathologists to enhance their role in cancer care as well as a challenge in managing the additional workload and complexity.
In the next post, I will discuss how digital pathology can aid pathologists in managing this information.