A biopsy is the analysis of a tissue sample. This article explains the importance of a biopsy in cancer care and clears up some misconceptions

1. A biopsy is required for the definitive confirmation of a diagnosis of cancer. A patient’s symptoms (what a patient complains of) and signs (what the doctor finds on physical examination) can sometimes lead to a suspicion of cancer.  A tentative diagnosis of cancer could be made on further evaluation like radiological tests (CT scan, MRI, PET-CT, etc), blood tests, or an endoscopy.  However, a final confirmation of a cancer diagnosis is by a biopsy.
2. The biopsy procedure is the method used to obtain tissue from the area of abnormality. The method used primarily depends on the location of the abnormality.  In the case of a superficially located tumor eg. on the skin, it could mean a painless sampling with a knife from the edge of the tumor under local anesthesia.  In the case of an internal organ like the gastrointestinal tract or the genitourinary tract, an endoscope may be required to access the area for sampling.  Sometimes an imaging tool like an ultrasonogram or a CT scan necessary to sample tissue from deep-seated organs.
3. The biopsy sample is the sample of tissue obtained during the biopsy procedure. For establishing a diagnosis, a sample about the size of a matchstick head is most often sufficient.  Sometimes multiple small samples from different representative parts of the abnormality are taken. At other times, especially in the case of a small-sized abnormality, the entire abnormality could be removed as the biopsy sample (excision biopsy) –  accomplishing both diagnosis as well as treatment in a single procedure.
4. The biopsy report is the information provided by the pathologist after processing the biopsy sample and examining it under the microscope.
5. A biopsy can provide a range of information.
   1. Diagnosis: Whether the abnormality is cancer or not.  If not, then an alternative diagnosis.
   2. Prognosis: Information about how slowly or quickly the cancer is likely to grow and spread based on type, grade, immunohistochemistry profile, etc
   3. Type of treatment required: Different types of cancer in the same organ may require different treatment. For example, squamous cell carcinoma of the anal region is best treated with chemoradiation, but melanoma requires surgery.
   4. Predictive value: Whether the tumor will respond to a particular medication. For example, hormone treatment is very useful for a patient with hormone receptor-positive breast cancer, but is of no use for someone with a hormone receptive negative breast cancer.
6. Negative biopsy report. As mentioned earlier, a diagnosis of cancer requires a positive biopsy confirmation by the pathologist.  However, a negative biopsy report (where the pathologist cannot see cancer in the examined biopsy sample) has to be interpreted carefully.  Because this topic needs to be understood in detail, it is the subject of a separate blog post.
7. Adverse effects of biopsy. Most often, a biopsy is a minor procedure, and complications are rare.  If complications do occur, they are usually minor and can include slight bleeding from the area where the sample was taken, minor pain or bruising.  Major complications are very rare and usually depends on the complexity of the technique required for the biopsy procedure.  Except under certain specific circumstances (which your oncologist/treating doctor will advise you about), performing a biopsy does not cause a cancer to spread.  The misconception that biopsy can cause cancer spread is quite common and often leads to delay or failure to seek treatment.

A proper biopsy is therefore a crucial weapon in the fight against cancer.