Biopsy means removal tissue samples from a suspected lesion. It is one of the most important diagnostic tools for detection and confirmation of certain cancers.
Types of biopsy
When cancer is suspected, a variety of biopsy techniques are applied. Some of these include:
An ''excisional biopsy'' is an attempt to remove an entire lesion. This also involves removal of the healthy margins around the lesion. "Clear margins" or "negative margins" means that no disease was found at the edges of the biopsy tissue. "Positive margins" means that disease has spread to the margins and a wider excision may be recommended.
An ''incisional biopsy'' involves removal of a wedge of tissue or a bite of tissue. A variety of sizes of needle can collect tissue in the lumen (‘’core biopsy’’).
Needle biopsy involves removal of a small sample of tissue from the lesion using a very fine needle. Needle or core biopsy may be guided with imaging studies like X ray, MRI or CT scan.
Endoscopic biopsy is usually performed with aid of endoscopy. An endoscope is a thin long flexible tube with a camera and instruments on tis tip. This is common for gastrointestinal tract lesions.
Biopsy on laparotomy or thoracotomy. When the whole tumor is removed for examination while operating on the patient, it is called laparotomy (opening up of the abdomen) or thoracotomy (opening up of the chest) biopsy. This is a form of excisional biopsy or open surgical biopsy.
When the sentinel node has been found, it is removed (an excisional biopsy) and looked at under a microscope. This is called sentinel lymph node biopsy.
Once the tissue is taken it is examined under the microscope for malignancy. The tissue sample is frozen into blocks and then sliced into microscopically thin slices. These slices are a single cell in thickness. These are then fixed onto a glass slide and stained with special dyes. The slides with the samples are then examined by a pathologist under the microscope.
Cancerous lesion biopsy
Microscopic examination of the lesion can say if the lesion is cancerous (malignant) or non-cancerous (non-malignant).
It can also determine the type of cancer. For example, there are various tissue types of cancer like Adenocarcinoma, Squamous cell carcinoma etc.
Examination also helps in grading the cancer. A low grade cancer is typically less aggressive and slow growing and slow spreading. On the other hand a high grade cancer is an aggressive form and spreads rapidly to distant organs.
Biopsy of cancer lesions helps in staging the cancer. An early stage cancer is typically localized while an advanced stage cancer has spread to lymph nodes and other organs like liver, lungs and brain.
Staging and grading of the cancer helps in planning treatment regimens appropriate for the type of cancer. It also helps to predict the possible outcome and survival. For example, an advanced cancer may mean a more intensive treatment regimen or palliative and symptomatic care alone. The patient in an advanced stage may not survive long.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)