CAP Member Pathologist Answers Cancer Questions
Cancer Q&A: Pathologists, oncologists collaborate to pinpoint treatment
By Dr. Wayne Duke
Daily Hampshire Gazette
Q. How is a biopsy handled?
A. Tissue specimens, otherwise referred to as biopsies, are initially placed in a preservative called formalin. The tissue is then processed into wax (paraffin) blocks to allow for the cutting of very thin slices by a specialized instrument called a microtome. These tissue slices are placed onto glass slides and stained to highlight the structure of the tissue. The biopsies are then examined under a microscope by a pathologist, who is a physician specially-trained in interpreting the slides.
Q. What are pathologists looking for in making a diagnosis of cancer compared to a benign lesion?
A. Initially, pathologists examine the tissue at low magnification to look for abnormal patterns in the structure of the tissue. Higher magnification is used to study individual cells and areas of concern.The vast majority of biopsies do not contain cancer, but rather an inflammatory condition or a benign growth. Infections can also be identified microscopically. Sometimes inflammatory conditions or benign growths can mimic a cancer and vice versa. However, the combination of many microscopic features usually determine if a cancer is present or not.
Q. How do you determine what type of cancer is present?
A. With broad medical knowledge and a keen eye, most types of cancer can be readily distinguished by a pathologist. If uncertainty exists, additional testing can be performed on glass slides using antibodies to identify the type of cancerous tumor present. This process is called immunohistochemistry.
Q. How long does it take to get a result?
A. Ninety percent of biopsy reports are completed within 48 hours of receipt of the tissue.
Q. What does grade and stage tell you and how do you determine that?
A. The grade commonly refers to the degree of abnormality present in the cancerous cells when seen under the microscope. The stage of most tumors is usually determined on larger specimens rather than on small biopsies. The stage usually reflects the tumor size, as well as how far the tumor has grown into the adjacent tissue, and whether it has spread to another site.
Q. How are modern molecular tests incorporated into the diagnostic process?
A. Molecular testing is now the standard of care for many tumor types and stages of cancer. These tests typically identify the genes/abnormal DNA that are fueling the disease. The testing is performed on the remaining tissue already present in the laboratory, where it was preserved in the paraffin block. Increasingly, the molecular analysis finds specific mutations or other changes that determine which drug or treatment will most likely to benefit the patient.
Q. What changes are on the horizon for pathologic testing?
A. It is an exciting time in the field of pathology and cancer care, as more and more therapies are being developed based on specific DNA mutations. The days of broad toxic chemotherapy regimens are diminishing as specific targeted therapies become available, determined by the tumor’s DNA which is analyzed in the molecular laboratory. In the coming years, most, if not all, tumors will be analyzed in a molecular laboratory and each patient given their unique medications to keep their cancer at bay. The days of living with, instead of dying from, cancer are becoming more and more common.
Dr. Wayne Duke is vice chairman of the department of pathology at Baystate Regional Medical Center and a member of the College of American Pathologists.
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