Introduction to Cancer

Definitions The word “cancer” comes from the latin word for crab. The Greek word oncos means swelling and where we get the word oncology or oncologist. What is the Latin word for swelling? Tumor

Neoplasia (Gk. new growth) “A neoplasm is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after cessation of the stimuli which evoked the change.” --Dr. R. A. Willis

Benign vs. malignant Well-differentiated - when cancer cells resemble normal surrounding cells. benign Poorly-differentiated – when cancer cells do not resemble normal surrounding cells. malignant

benign – well-differentiated.

malignant-poorly differentiated

Benign: grow slowly low mitotic rate well differentiated not invasive; well-defined borders remain localized; do not metastasize

Malignant Grow rapidly high mitotic index poorly differentiated do not have a capsule invade surrounding structures; can metastasize

Nuclei of cells Have an abundance of DNA and are therefore large. Hyperchromatic- stain darkly

In contrast, this hepatocellular carcinoma is not as well circumscribed (note the infiltration of tumor off to the lower right) nor as uniform in consistency. It is also arising in a cirrhotic (nodular) liver.

Malignant neoplasms are also characterized by the tendency to invade surrounding tissues. Here, a lung cancer is seen to be spreading along the bronchi into the surrounding lung.

This is an example of metastases to the liver This is an example of metastases to the liver. Note that the tan-white masses are multiple and irregularly sized. A primary neoplasm is more likely to be a solitary mass. Metastasis is the best indication that a neoplasm is malignant.

Stages of cancer spread: Stage 1 – confined to site of origin Stage 2- cancer is locally invasive Stage 3 – cancer has spread to regional structures Stage 4- cancer has spread to distant sites

TNM system: tumor spread node involvement presence of distant metastasis Staging may influence choice of treatment

Staging TNM system Size of tumor – T0, T1, T2,T3 Degree of local invasion – lymph node involvement Extent of spread – metastasis

Patterns of spread: Metastasis Direct or continuous extension By lymphatics or blood stream As clumps or as single cells Lymphatics most common

Distribution and common sites of distant metastases often occurs in the first capillary bed encountered Others show “organ tropism” Due to: Local growth factors or hormones Preferential adherence to the surface Presence of chemotactic factors

Clinical manifestations of Cancer Pain Usually not in early stages 60 – 80 % of terminally ill Psychogenic, cultural and physiologic components Due to pressure, obstruction, stretching, tissue damage or inflammation

Clinical manifestations of Cancer Cachexia – wasting anorexia early satiety weight loss anemia marked weakness taste alterations altered metabolism

Clinical manifestations of Cancer Anemia chronic bleeding malnutrition medical therapies malignancy in blood forming organs Administer erythropoietin

Clinical manifestations of Cancer Leukopenia and thrombocytopenia tumor invasion of bone marrow chemotherapy or radiation

Cancer Treatment Chemotherapy Cytotoxic drugs + body defenses Single agent Combination chemotherapy Avoids single agent resistance Can use lower dose Better remission and cure rate

Cancer Treatment Radiation targets DNA kill tumor without damage to surrounding tissues tumor must be accessible

Cancer Treatment Surgery method of choice can remove entire tumor debulking adjuvant chemotherapy or radiation palliation