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Cancer - General Information
A tumor is an abnormal growth of tissue that occurs in the body. Tumors can be benign (non-cancerous) or malignant (cancerous). Benign tumors may grow in the organ in which it developed, but generally do not spread to other organs. An example of this is prostate enlargement, also called BPH (benign prostatic hyperplasia). In this condition, non-cancerous prostate tissue proliferates within the prostate to cause symptoms of urinary obstruction. This process is limited to the prostate.
Malignant tumors, however, have the ability to grow in the organ from which developed, invade other adjacent organs, or spread to other distant organs in the body. An example of this is prostate cancer. While the majority of prostate cancer detected in the U.S. is localized to the prostate, prostate cancer may invade tissues around it, spread to lymph nodes or bone in advanced states.
Type
Each organ has a specific type of cell associated with that organ. When viewed under a microscope, Pathologists can usually tell the organ of origin of the cancer and the characteristics associated with that tumor.
Grade
Each tumor is assigned a grade. Grade is assigned by a Pathologist and refers to how cancer cells appear under the microscope. Each cell (or group of cells) has characteristic features which make it a lower grade (less aggressive) or higher grade (more aggressive tumor). There has been an ongoing effort by the World Health Organization (WHO) to standardize the language of grading tumors.
- Grade 1 - low grade, lower malignant potential (well-differentiated)
- Grade 2 - moderate grade, moderate malignant potential (moderately-differentiated)
- Grade 3 - high grade, high malignant potential (poorly-differentiated)
- Grade 4 - high grade, high malignant potential (poorly-differentiated)
It should be noted that prostate cancer is unique in its grading system. Dr. Gleason developed the Gleason Grading System which can be reviewed in the section under prostate cancer.
Stage
Each tumor is assigned a stage. Stages can be designated clinical stage (based on exam, tumor biopsy if applicable, and x-ray studies) or pathological stage (based on pathogical exam of organ and tumor removed, and x-ray studies). The World Health Organization (WHO) has attempted to standardize the staging system for solid organ tumors. The standard staging system is the TNM system as outlined below. Please note, these are general categories and will vary depending on the specific type of cancer.
- T Stage - extent of tumor involvent in organ or adjacent tissue
- T0 - no tumor
- T1 - tumor generally limited to organ, low volume
- T2 - tumor generally limited to organ, higher volume
- T3 - tumor generally extends beyond capsule or boundary of organ
- T4 - tumor generally invades surrounding/adjacent organs
- N Stage - extent of tumor involvement in lymph nodes
- N0 - no lymph node involvement by tumor
- N1-3 - tumor involves lymph nodes, increasing involvement as N number increases
- M Stage - extent of tumor involvement in distant (unrelated organs)
- M0 - no evidence of metastatic disease
- M1 - evidence of metastatic disease
Example:
Dr. Smith performs a bladder tumor resection on Mr. Jones. A CT scan, chest x-ray, and bone scan are performed. The bladder tumor is reviewed by the pathologist. Mr. Jones then meets with Dr. Smith for a consultation. At that time, Dr. Smith determines that Mr. Jones' tumor is a cT2N0M0. This means:
- c- this prefix indicates clinical staging (if he bladder was removed, the prefix would be p)
- T2 - tumor extends into but not through the wall of the muscle of the bladder
- N0 - tumor does not involve lymph nodes (based on CT)
- M0 - tumor does not involve distant organs (based on CT, chest x-ray, and bone scan)
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