Download Characteristics of benign and malignant tumors Features of

Characteristics of benign and malignant tumors
-( Oral Surgery hand-out) semester 9
Tumour is characterized as an excessive, chaotic growth of cells, which morphologic features are the derivative of m
malignancy.
Clinical division of neoplasms:
-Benign neoplasm (neoplasma benignum)
Benign neoplasms in composition differs little from its matrix tissue
-Semimalignant neoplasm (neoplasma semimalignum)-locally malignant neoplasm
-Malignant neoplasm (neoplasma malignum)
Malignant neoplasms in composition differs from its matrix tissue
Histopathologic division of cancer
-G
X – stage of differentation imposible to evaluation
-G1 – well differentiated cancer
-G2 – differrentation of medium stage
-G3 – low differentiated cancer
-G4 – indifferentiated cancer
Types of neoplasms developing in the jaw bones:
Neoplasms developing in the jaw bones can be divided into two types:
–Odontogenic neoplasms, characteristic for jaw bones
–Neoplasms of mezodermal origin occuring also in other parts of the skeletal system
Preinvasive cancer (carcinoma in situ)
It is a primary neoplasm that developes within the epithelium, not exceeding its basic layer
It is the pre-clinical stage of a cancer in which the chances for recovery are the best ones.
Precancerous conditions
TNM classification:
Clinical classification
•Stage I
•Stage II
•Stage III
•Stage IV
T1 N0 M0
T2 N0 M0
T3 N0 M0
T1T2T3 N1 M0
T4 N0N1 M0
T1T2T3T4 N2N3 M0
T1T2T3T4 N1N2N3 M0
Features of benign tumours
Features of semimalignant tumours
Features of malignant tumours
Etiology and pathogenesis of head and neck cancer
A variety of environmental, toxic, and viral agents have been implicated in head and neck carcinogenesis
The particular carcinogenic mechanisms of some of these agents have been well studied and identified, e.g.:
– tobacco
– ionization radiation
– oncogene viruses
•Other factors such as: poor oral hygiene, dietary deficiencies, certain occupational exposures
are linked to head and neck cancers in epidemiologic studies but lack evidence linking them to specific carcinogenic
mechanisms
•By convention the cell cycle initiates in the Gap 1 (G1) phase in which the cell monitors the external environment
for the presence or absence of particular growth-promoting (or growth-inhibiting) signals
•If appropriate signals are present for the cell division, then the cell will proceed into the period of DNA synthesis
(S phase). Once DNA replication is complete the cell will again "survey" the environment during a second Gap
phase (G2).
•If the environment is favourable and the DNA is replicated correctly, then the cell will enter mitosis (M phase) and
subsequently divide successfully
•Most common, however, are epidermoid carcinomas of the oral mucosa, which are form of cancer that the dentist is
in a position to discover first by doing thorough oral examination
Malignant tumours of the oral cavity
Malignancies of the oral cavity may arise from a variety of tissues, such as salivary glands, muscle, and blood
vessels, or may even present as metastases from distant sites
The seriousness of an oral malignancy can vary from the necessity for a simple excissional biopsy to composite jaw
resection with neck dissection (i.e., removal of the lymph nodes and other visceral structures adjacent to lymph node
channels in neck)
Clinical staging
Because of the variation in clinical presentation, clinical staging is usually undertaken before a treatment plan is
formulated
It refers to assessing the extent of the disease before undertaking treatment and has two purposes:
Selection of the best treatment, and meaningful comparison of the final result reported from different sources
Clinical staging of the lesions is performed for several varietes of oral malignancies, including epidermoid
carcinomas and oral lymphomas
Staging is performed differently for each type of malignancy and may involve extensive diagnostic tests, such as
radiographs, blood tests, and even surgical exploration of other body areas to evaluate the extent of possible tumour
metastasis
•Once the tumour is staged, treatment is formulated
Several types of malignancies have well-defined treatment protocols that have been designed by surgeons and
oncologists in an effort to study the effectiveness of treatment regimens more carefully
Treatment modalities for malignancies:
Malignancies of the oral cavity are treated with surgery, radiation, chemiotherapy, or a combination of these
modalities
The treatment for any given case depends on several factors, including:
•The histopathologic diagnosis
•The location of the tumour
•The presence and degree of metastasis
•The radiosensitivity or chemosensitivity of the tumour
•The age and general physical condition of the patient
•The experience of the treating clinicians
•The wishes of the patient
In general, if a lesion can be completely excised without mutilating the patient, this is the preferred modality
•If spread to regional lymph nodes is supected, radiation may be used before or after surgery to help eliminate small
foci of malignant cells in the adjacent areas
•If widespread systemic metastasis is detected or if a tumour, such as lymphoma, is especially chemosensitive,
chemotherapy is used with or without surgery and radiation
•Malignancies are often treated in an institution where several specialists evaluate each case and discuss treatment
regimens
These „tumour boards” include at least a surgeon, a chemotherapist, and a radiotherapist
•Most head and neck tumour boards also include a general dentist, a maxillofacial prosthodontist, a nutritionist, a
speech pathologist, and a sociologist or psychiatrist
Radiotherapy
Fractionation
Multiple ports
Chemotherapy
Surgery