How do malignant neoplasms develop?
Malignant tumors are cancerous. They develop when cells grow uncontrollably. If the cells continue to grow and spread, the disease can become life threatening. Malignant tumors can grow quickly and spread to other parts of the body in a process called metastasis.
What is the first step in tumor development?
The first step in the process, tumor initiation, is thought to be the result of a genetic alteration leading to abnormal proliferation of a single cell. Cell proliferation then leads to the outgrowth of a population of clonally derived tumor cells.
What is the sequence of tumor development?
Tumors typically progress is a stepwise fashion: Hyperplasia – cells divide too much but appear normal. Dysplasia – the tumor cells and tissue appear abnormal. Carcinoma in situ – tumor contains primarily altered cells and is growing larger; it has not left the site of origin.
What are the 3 stages of carcinogenesis?
The process of carcinogenesis may be divided into at least three stages: initiation, promotion, and progression.
What is neoplasm disease?
(NEE-oh-PLA-zum) An abnormal mass of tissue that forms when cells grow and divide more than they should or do not die when they should. Neoplasms may be benign (not cancer) or malignant (cancer).
What are the 4 stages of carcinogenesis?
Carcinogenesis can be divided conceptually into four steps: tumor initiation, tumor promotion, malignant conversion, and tumor progression (Figure 17-1). The distinction between initiation and promotion was recognized through studies involving both viruses and chemical carcinogens.
Which of the following are key steps in metastasis?
Metastatic progression of solid tumors can be divided into five major steps: (1) invasion of the basement membrane and cell migration; (2) intravasation into the surrounding vasculature or lymphatic system; (3) survival in the circulation; (4) extravasation from vasculature to secondary tissue; and finally, (5) …
What triggers carcinogenesis?
Carcinogenesis appears as a multistage process at molecular level, being triggered either by the action of retrovirus oncogenes, which all induce RNA synthesis and cell division, or by the disturbed, abnormal activity of protooncogenes, one cellular oncogenes .
What is the initiation stage of carcinogenesis?
Carcinogenesis occurs in four stages: initiation. promotion, progression, and malignant conversion. Initiation involves the interaction of the carcinogen with DNA, producing either a strand break or adduct. An adduct is an altered nucleotide which,.