The diagnosis of cancer is usually made by taking a portion of the tumor and looking at it under a microscope. This is called a biopsy. There are three different types of biopsies. If we remove all of the lump, it is called an excisional biopsy. If we remove part of the lump, it is called an incisional biopsy. If we use a needle to obtain a small part of the lump, it is called a needle biopsy.
Needle biopsy: a needle is inserted into a lump and a few cells are withdrawn into the needle. The cells are placed on a glass microscope slide, sent to the lab, stained, and looked at under the microscope (like a Pap smear). Sometimes this will tell us if the lump is a cancer. However, this test has its limitations, and we usually do not rely completely on this for diagnosis.
Incisional or excisional biopsies are procedures done in the hospital operating room. Usually the entire tumor is removed and sent to the pathologist. He is the physician who will look at the lump under a microscope and give us a diagnosis. The day that a biopsy is done he may freeze a small piece, take a thin slice and look at it right away. This is called a frozen section. The frozen section can usually give us an answer; but not always. We rely on the permanent section report for the final determination. The permanent sections are made by soaking the specimen in paraffin (wax) overnight. This allows very precise, thin slices to be made. When these are viewed under the microscope, the clarity is greater than that of the frozen section. Also, the pathologist has the time to look at many different areas of the tissue removed when he makes the permanent sections; so he can give us more information about the relationship of the tumor to the surrounding tissue.
The main difference between a needle biopsy and an excisional biopsy is that with a needle biopsy, the pathologist is looking at individual cells and trying to determine if they have characteristics that make them look like cancer cells. When an excisional biopsy is performed, the pathologist looks at both the characteristics of the cells and how they are interacting with the neighboring cells. This is called a histologic section and is considered more accurate than a needle biopsy.
Evaluation for Metastatic Disease
When a patient is first diagnosed as having cancer, we want to know if the cancer has spread. Although there are many types of tests, only a few of them are recommended. Researchers have found that if a patient has no symptoms, nor any findings on physical examination to suggest spread, only a few tests are worth doing. Although there are literally dozens of tests that could be done, the chance of finding anything in an asymptomatic patient is so low that it is not worth the cost and inconvenience. The tests that are usually considered appropriate are physical examination, chest x-ray, liver function tests (a blood chemistry test), urine analysis and PET or CT scan.