Mesenchymal (connective tissue, blood or lymphatic tissue) cancers have a specific naming system. There is a prefix for different types of tissue that make up the tumor and a suffix to signify whether it is benign or malignant. However, Cancers of blood cells (Leukemia) and lymph nodes (Lymphoma), both of which are always malignant, do not follow this pattern.
Prefix + OMA = Benign Mesenchymal Cancer
Prefix + SARCOMA = Malignant Mesenchymal Cancer
Mesenchymal Cancer Prefix
- Lipo- = Fat
- Osteo- = Bone
- Fib- = Fibrous Tissue
- Chondro- = Cartilage
- Hemangio- = Blood vessel
- Leiomyo- = smooth muscle
- Rhabdomyo- = striated muscle
Cancers that originate from epithelium (glands and surface/cavity lining) have a naming system that is more complicated. Benign epithelial cancers that contain glandular tissue (such as prostate, adrenal glands and certain types of colon cancer) are called Adenomas. Adenomas often grow into the lumen of whatever organ they are in forming a Polyp. Cystadenomas are hollow cysts-like cancers that are usually filled with fluid. Benign cancers of stratified squamous epithelium that form “cauliflower” finger like projections are called Papillomas. Malignant epithelial cancers are called Carcinomas.
Metastasis is the spread of a cancer from the original tumor location to “distant” sites in the body. This is generally thought of as being separate from cancer invasion, which is the direct extension of a cancer across an organ or to neighboring organs. Invasion is a tumor growing in size and taking up more space, while metastasis involves migration to a completely new site. Metastasis is the most important prognostic factor for a cancer and is represented by the cancer’s Stage (More important than the cancer’s level of differentiation or grade).
Metastasis is usually via the lymphatic system or the blood vessels. In this way, the cancer cells use the lymph or blood as a highway to get to other sites in the body. Carcinomas tend to spread via the lymph while sarcomas more commonly spread via blood, but there are numerous exceptions to this general rule.
Carcinoma = Lymphatic Spread
Sarcoma = Hematologic (Blood) Spread
To be able to spread cancer cells need certain abilities which are gained via additional mutations. These mutations allow the cancer cells to break away from the primary tumor, “eat” through the basement membrane (Type IV Collengenase), “eat” through the extracellular matrix (Metalloproteinases), enter the lymphatics/blood, survive travel in the fluid, exit lymphatics/blood, and survive in the new site.
The original mass is called the primary tumor while all subsequent masses are secondary tumors. Cancers can spread almost anywhere once they are in the lymph or blood, but the location of secondary tumor sites is not random. The circulatory anatomy and how accommodating certain tissues are to cancers mean that secondary tumors arise in certain areas most often. Due to these tendencies the most likely location of metastasis can often be predicted.
Secondary Tumor: Most likely Primary Tumor:
- Liver GI cancers like colon cancer
- Brain (gray-white junction) Lung & Breast
- Bone (spine) Prostate (blastic), Lung (lytic) & Breast (Both)
- Lung Breast
Liver Metastasis is most common among cancers that arise in the GI tract (Like colon cancer), which makes sense as the liver receives blood from the GI tract through portal venous system. The Brain Metastasis usually present at the Gray-White matter junction. This is because the width of the vessels changes quickly at this junction and metastatic “emboli” are more likely to lodge here. Metastatic brain cancer generally presents as multiple lesions while a primary brain cancer is usually a single lesion. Lung and Breast are the most common primary site for brain metastasis. Lung Metastasis is most often from breast cancer. Primary bone cancers are rare, but Metastasis to Bone is relatively common. Metastasis to the spine (resulting in low back pain) from the prostate is a common presentation in step 1 questions. Different primary tumors have unique secondary bone cancer characteristics. Lytic lesions are where increased osteoclast activity eats away at the bone and releases calcium (seen as hypercalcemia). Blastic Lesions are where increased osteoblastic activity results in more bone being laid down than normal.
1o Lung Cancer –> osteoLytic 2o Bone Cancer
1o Prostate Cancer –> osteoblastic 2o Bone Cancer
1o Breast Cancer –> Both lytic and blastic 2o Bone Cancer