The first step in the diagnosis of cancer is to perform a “biopsy”. A biopsy is the taking of a small body tissue sample from the suspected area to examine it very closely under a microscope. Biopsies are usually taken during medical tests or operations. For example, a patient may be having an endoscopy - an examination that looks at the inside of the oesophagus (gullet) and stomach.

If the doctor sees signs of stomach ulceration, small tissue samples will be cut out and sent to the laboratory. The cells in these samples of tissue will be looked at very closely under the microscope to see if they are normal or cancer cells. If they were normal, then the patient would be diagnosed with a stomach ulcer. If they looked cancerous, then he/she would be diagnosed with stomach cancer.

Cancer cells look quite different from normal cells. They are often more primitive looking and have oddly shaped nuclei compared to a normal cell. Even so, one can usually tell what type of body cell it was originally. Doctors can sometimes tell, from biopsies, where in the body a cancer has started.

TYPES OF BIOPSIES

1. Excisional biopsy
   This type of biopsy involves the removal (excision) of an entire organ or lump. These are less common now, since the development of fine needle aspirations (see below). Some types of tumors (such as lymphoma, a cancer of the lymphocyte blood cells) have to be examined as a whole, to allow an accurate diagnosis. Hence, enlarged lymph nodes are good candidates for excisional biopsies. Some surgeons prefer excisional biopsies of most breast lumps to ensure the greatest diagnostic accuracy. Some organs, such as the spleen, are dangerous to cut into without completely removing it, so excisional biopsies are preferred in such cases.
2. Incisional biopsy
   An incisional biopsy involves only portional surgical removal of the lump. This type of biopsy is most commonly used for tumors of the soft tissues (muscle, fat, connective tissue) to distinguish benign conditions from malignant soft tissue tumors, called sarcomas.
3. Endoscopic biopsy
   The endoscopic biopsy is probably the most commonly performed type of biopsy. It is done through a fiber optic endoscope that the doctor inserts into the gastrointestinal tract (alimentary tract endoscopy), urinary bladder (cystoscopy), abdominal cavity (laparoscopy), joint cavity (arthroscopy), mid-portion of the chest (mediastinoscopy), or trachea and bronchial system (laryngoscopy and bronchoscopy), either through a natural body orifice or a small surgical incision. The endoscopist can directly visualize an abnormal area on the lining of the organ in question and pinch off tiny bits of tissue with forceps attached to a long cable that runs inside the endoscope.
4. Colposcopic biopsy
   This is a gynecologic procedure that is typically used to evaluate a patient who has an abnormal Pap smear results. The colposcope is actually a close-focusing telescope that allows the physician to see, in detail, abnormal areas on the cervix of the uterus. This allows for good representation of the abnormal area where samples may be removed and sent to the pathologist.
5. Fine needle aspiration (FNA)
   The FNA is another type of biopsy that is an extremely simple technique. It traces its origin to and has been used in Sweden for decades, but has only recently developed widely in the US over the last ten years. A needle no wider than that typically used to give routine injections (about 22 gauges) is inserted into a lump (tumor), where tens to thousands of cells are drawn up (aspirated) into a syringe. These cells are smeared on a slide, stained, and examined under a microscope by the pathologist. A diagnosis can often be rendered within minutes. Tumors of deep, hard-to-get-to structures (pancreas, lung, and liver, for instance) are especially good candidates for FNA, as the only other way to sample them is through major surgery Thyroid lumps are also excellent candidates for FNA. Such FNA procedures are typically done by a radiologist under the guidance of ultrasound or computed tomography (CT scan). The procedure requires no anesthesia, not even local.
6. Punch biopsy
   This technique is typically used by dermatologists to sample skin rashes and small masses. After a local anesthetic is injected, a biopsy punch, which is basically a small (3 or 4 mm in diameter) version of a cookie cutter, is used to cut out a cylindrical piece of skin. The hole is typically closed with a suture and heals with minimal scarring.
7. Bone marrow biopsy
   In cases of abnormal blood counts, such as unexplained anemia, high white cell count and low platelet count, it is necessary to examine the cells of the bone marrow. In adults, the sample is usually taken from the pelvic bone, typically from the posterior superior iliac spine. This is the prominence of bone on either side of the pelvis underlying the "bikini dimples" on the lower back/upper buttocks. Hematologists perform bone marrow biopsies all the time, but most internists, pathologists and many family practitioners are also trained to perform this procedure.

The patient is instructed to lie down, while the skin over the biopsy site is deadened with a local anesthetic. The needle is then inserted deeper to deaden the surface membrane covering the bone (periosteum). A larger rigid needle with a very sharp point is then introduced into the marrow space. A syringe is attached to the needle and suction is applied. The marrow cells are then drawn into the syringe. This suction step is occasionally uncomfortable, since it is impossible to numb the inside of the bone. The contents of the syringe, which to the naked eye looks like blood with tiny chunks of fat floating around in it, is dropped onto a glass slide and smeared out. After staining, the cells are visible to the examining pathologist or hematologist.

This part of procedure, the aspiration, is usually followed by the core biopsy, in which a slightly larger needle is used to extract core bone samples. The calcium is removed from the bone to make it soft, the tissue is processed (see "Specimen Processing," below) and tissue sections are made. Even though the core biopsy procedure involves a bigger needle, it is usually less painful than the aspiration. Bone marrow aspirate and biopsy can be done under sedation for young patients and if the patient is very anxious.

Staging
It is very important to identify the exact spread of disease, both in the area of the primary tumor or where it has spread to other body organs. Depending on the type of cancer, oncologists may order the following tests to “stage” cancer:

• Magnetic Resonance Imaging (MRI): particularly useful in tumors of the extremities and brain.
• Computed Tomography (CT): very useful to look at tumors that have spread in the lungs, abdomen and pelvic organs.
• Bone scan: detects areas of cancer spread in the bones.
• Bone marrow biopsy: detect the presence of cancer cells in the bone marrow.
• PET/CT scan: A study that uses radiolabeled sugar. Malignant tumors take more sugar and become “hot” on the scan.
• Gallium scans: usually used on lymphoma patients and is being replaced by PET/CT scanning.
• Sentinel lymph node biopsy: a special procedure that is typically done in cases of sarcoma, breast cancer and melanoma to detect the presence of cancer cells in lymph nodes.