**5. Altered cellular metabolism in canter cells (Warburg effect)**

Cancer cells have different needs than their normal counterpart. Their proliferative rate generally exceeds that of normal cells. Cancer cells must quickly synthesize the structural components (e.g., protein, lipid, etc.) that are required for rapid cell growth (that is to sustain their mitotic activity).

With adequate oxygen supply, cancer cells undergo a metabolic switch to aerobic glycolysis. They develop a distinctive form of cellular metabolism characterized by



#### **Table 4.**

*Selected oncogenes, their mode of activation, and associated human tumors.*


#### **Table 5.**

*Cell cycle components and inhibitors that are frequently mutated in cancer.*

increased amount of glucose uptake and increased conversion of glucose to lactose (fermentation) via the glycolytic pathway. This aerobic glycolysis is called the Warburg effect. It was described in 1930 by Otto Warburg and is not cancer-specific but observed in growing cells and it becomes "fixed" in cancer cells. It is seen because tumor cells have M2 isoform of pyruvate kinase enzyme.

Aerobic glycolysis provides metabolic intermediates that are needed for the synthesis of cellular components in rapidly dividing tumor cells. This cannot be met with normal mitochondrial oxidative phosphorylation.



**Table 6.**

*Selected tumor suppressor genes and associated familal syndromes and cencer. Sorted by Cancer Hallmarks.*

Clinical utility: The "glucose-hunger" of tumors is made for visualization of tumors in positron emission tomography (PET) scanning. In PET scanning, patients are injected with 18F-fluorodeoxyglucose (a8-FDG- a non-metabolizable derivative of glucose) which is preferentially taken up into tumor cells (and also actively dividing normal cells, for example., bone marrow cells). Most tumors are PET-positive, and markedly positive are the rapidly growing tumors [15].

#### **6. Invasion and metastasis**

#### **6.1 Locally malignant tumor**

Definition: The malignant tumors that are locally invasive but show little or no tendency to metastasize are called locally malignant tumors.

*Neoplasia DOI: http://dx.doi.org/10.5772/intechopen.109512*

	- 1.Basal cell carcinoma of skin.
	- 2.Glioma/glial cell carcinoma of central nervous system.
	- 3.Giant cell tumor of bone.
	- 4.Ameloblastoma.
	- 5.Craniopharyngioma.
	- A. Benign tumor:
		- Grow as cohesive expansile masses.
		- Remain localized to their site of origin.
		- Do not have the capacity to infiltrate, invade, or metastasize to distant sites.
		- Sometimes they develop a fibrous capsule.
	- B. Malignant Tumor:
		- Invasive and can be expected to penetrate the wall.
		- Such invasiveness makes their surgical resection difficult.
