The Metastasic Event In The Temporal Progression Of Cancer

Tumorigenesis is a multistep process associated with accumulated genetic alterations in somatic cells.3 The progression of a tumor through preneo-plasia to frank neoplasia and then invasion and metastasis is the result of successive rounds of clonal expansion of somatic cells that acquire a selective growth advantage as a result of mutations in genes that control cellular proliferation and death (Table 4.1).7,8 Figure 4.1 is a schematic representation of tumor progression including multiple sequential steps involving host-tumor interactions. Although modern medical technology permits early detection of neoplasias, most tumors manifest or are detected relatively late in the progression after the tumor has acquired cell heterogeneity as result of spontaneous mutations and chromosomal abnormalities. This heterogeneity, detected at clinical presentation of tumors, indicates higher growth rates and greater metastatic potential.

TABLE 4.1. Carcinogenic Steps During the Metastatic Cascade.

Step

Characterized by

I. Tumor initiation II. Promotion and progression

III. Uncontrolled proliferation

IV. Angiogenesis

V. Invasion of tissues, blood vessels, and lymphatic channels

VI. Vascular endothelial cell tumor arrest and extravasation

VII. Tumor growth at secondary sites

VIII. Evasion of host defenses and resistance to therapy

Carcinogenic insult; gene and chromosomal disarrangements Gene amplification; inactivation of suppressor genes Growth factors and hormones Multiple stimulating and promoting factors Metalloproteinases; loss of MTP inhibitors, receptors, and adhesion molecules Adhesion molecules and receptors; MTP; chemotaxis factors Homing factors, angiogenesis, growth factors Surpass macrophages; natural killer cells and blocking of T-cell response; expression of drug-resistant genes

Source: Modified from Liotta LA, Kohn EC. Invasion and metastasis. In: Bast RC, Kufe DW, Pollock RE, et al, eds. Cancer Medicine. 5th ed. New York: BC Decker; 2000:121-131.

Source: Modified from Liotta LA, Kohn EC. Invasion and metastasis. In: Bast RC, Kufe DW, Pollock RE, et al, eds. Cancer Medicine. 5th ed. New York: BC Decker; 2000:121-131.

Was this article helpful?

0 0
10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment