INTRODUCTION TO ONCOLOGY

INTRODUCTION TO ONCOLOGY

I -DEFINITION:

II – GENERAL NOMENCLATURE AND TERMINOLOGY:

1. THE BASICS OF NOMENCLATURE:
   1. 1°-the morphological bases:
   2. 2°-the embryological bases:
   3. 3°-the anatomo-clinical bases:
2. CONCEPT OF UNITED OR MULTI-ISSULAR TUMOR:
   2. Unitissular tumors 
   3. Monodermal multitissue tumors  
   4. Multi-tissue and polydermal tumors  
3. THE MAIN CATEGORIES OF TUMORS:

1. Tumors of epithelial structures
2. Tumors of mesenchymal structure
3. Tumors of neuroectoblastic structures

• neuroectodermal tumors proper
• mesectodermal tumors 

4. Tumors of embryonic structure: 
5. Composite structure tumors
6. TERMINOLOGY DIFFICULTIES:

III – TUMOR, SWELLING AND CELLULAR PROLIFERATION:

1. tumor and inflammation:                                                                  
2. tumor and hyperplasia:
3. tumor and dystrophy:          
4. relationship between tumor and pseudotumor:

IV – PLACE OF PATHOLOGY (Pathological Anatomy and Cytology):

INTRODUCTION TO ONCOLOGY

I -DEFINITION:

              Oncology is the science of tumors (from oncos = mass, volumes.

              One of the simplest definitions of the word tumor (tumor = swelling) is to state that it is a persistent cellular construction, resulting from the normal growth of cells born on site.

             In another way, we can specify that a tumor is a tissue mass due to the development at a point in the organism of a new cell line, not subject to the local and general rules of homeostasis . Tissue homeostasis corresponds in this case to maintaining the balance between cell losses by death following senescence or any other pathological process, and their renewal in adequate quantity by new cells differentiating normally and becoming identical to those they replace. We deduce, in this perspective, that a tumor is a new tissue whose cells proliferate by demonstrating biological autonomy in relation to the organism that carries it and that we call the host.

              This new tissue character explains the terms neoplasm, neoplasia, neoformation (from neo = new, plasm = to form, plaseis = formation), often used as a synonym for tumor.

              The local accumulation of tumor cells produces tissue changes that can be detected as soon as they appear by histopathological examination, if there is any reason to suggest doing so.

              It usually also results in an anatomical deformation such as an intumescence; but this must have required a certain volume after a more or less long evaluation time, to become appreciable to the naked eye, by X-ray or by any other investigative procedure.

II – GENERAL NOMENCLATURE AND TERMINOLOGY:

              The etiology and pathogenesis of tumors remain too obscure for a methodical and satisfactory classification to be proposed today. It has become essential, however, to draw up their nomenclature (from nomen callere = to call by name); that is, to provide a practical catalogue as complete as possible, even if the terminology used is not absolutely logical.

              Such nomenclature is explained by a daily need to use definitions, always the same: it is the only way to validly exchange diagnostic protocols, therapeutic prognosis and medico-social monitoring, and to establish statistics and epidemiological surveys.

A – THE BASICS OF NOMENCLATURE:

              They have decomposed over the years before even the use of the microscope.

1°-the morphological bases:

              The structure of a tumor generally resembles that of the tissue in which it originates and which is called: matrix tissue (= homologous tissue = original tissue).

2°-the embryological bases:

              Some tumors have an architecture very similar, if not identical, to that of the tissues that arise from the three primordial layers:                         

• ectoblastic,
• mesoblastic, 
• endoblastic,   

              Or even a blastema , at any stage of embryogenesis or organogenesis.

3°-the anatomo-clinical bases:

              Medical experience teaches us that there are two main groups of tumors.      

              Some of them push back the surrounding tissues without invading them, remain localized and are made of cells that do not proliferate much, generally well differentiated: these are benign tumors .

              The others destroy the surrounding tissues by invading them, give rise at a distance to daughter tumors called  metastases (from metistemein = to change place) and are made of differentiated or non-differentiated proliferating cells, these are malignant tumors or cancers (cancer = crab).

              This separation does not exactly correspond to reality. 

              Some undifferentiated or poorly differentiated tumors have a simple local malignancy, evolve slowly without causing metastases or almost never and always late, which are sometimes called tumors with attenuated malignancy. 

              Others, with a very differentiated histopathological structure, behave in the opposite manner, in a lightning-fast manner and kill their host a few weeks or months after their clinical discovery.  

              It must therefore be admitted that, given the current state of our knowledge, no one can give an irrefutable scientific definition of tumors and always separate with certainty what is a benign tumor from what is a malignant tumor.

B – CONCEPT OF UNITED OR MULTI-ISSULAR TUMOR:

              Tumors are divided into three groups according to their tissue component:

1. Unitissular tumors: represent the vast majority. They are made up of a single tissue type from which the neoformation has developed.
2. Monodermal multi-tissue tumors: are made up of several tissue types, each of which is reminiscent in its structure of tissue from a single embryonic stem (an embryonic layer or one of its derivatives).
3. Multi-tissue and polydermal tumors: are composed of a complex assembly of tissues resembling structures arising from two or even three primordial layers.

INTRODUCTION TO ONCOLOGY

C – THE MAIN CATEGORIES OF TUMORS:

              By taking into consideration the appearance of the newly formed structures and their benign or malignant behavior, we obtain the necessary elements to divide tumors into several schematic categories while leaving aside histogenetic and pathogenetic theories.

1. Tumors of epithelial structures : are most often unit-tissue.

• benign epithelial tumors
• malignant epithelial tumors (=carcinoma = epithelioma; from the Greek carcinos = crab)

2. Tumors of mesenchymal structure : most often unit-tissue.

• benign mesenchymal tumors;
• malignant mesenchymal tumors (=sarcoma; from the Greek sarx = flesh)

3.  tumors of neuroectoblastic structures : most often unit-tissue.

• neuroectodermal tumors proper : these are
• Central nervous system tumors , especially  neuroglia  

      (gliomas) and the lining of the cerebrospinal cavities (ependymoma, 

      choroid plexus tumor).

• mesectodermal tumors : these are

• meningeal tumors (meningiomas);
• tumors of the sympathetic and parasympathetic nerve ganglia :

  (embryonic sympathoma; ganglioneuroma; chemodectoma);

• Schwann sheath tumors (schwannoma; neurofibroma);
• tumors of the melanogenetic system : (pigmented nevus; melanoma 

  smart ) ;

• diffuse endocrine system tumors .

4. Tumors of embryonic structure  : are single or multi-tissue.

• benign or malignant tumors whose structure, simple or complex, recalls that of embryonic tissue or a blastema:
  • embryonal sarcoma
  • renal blastoma tumors (nephroblastoma)
  • hepatic blastoma tumors (hepatoblastoma)
    • benign or malignant tumors whose structure, simple or complex, recalls one or more of the aspects through which tissues pass from the first stages of embryogenesis to the adult state = teratoma, dysembryoma.

5. Tumors with a composite structure : are single or multi-tissue.

• benign tumors :
  • Epithelial: benign adenoacanthoma etc.
  • Mesenchymal: fibrolipoma, angiomyolipoma , etc.
  • Epithelial-mesenchymal: adenofibroma, adenomyoma…
    • malignant tumors :
      • Epithelial: adenosquamous (malignant adenoacanthoma)

                        Both components (glandular and epidermoid) are malignant.

• Mesenchymal:   mesenchymoma;
• Epithelial-mesenchymal:   carcinosarcomas,

INTRODUCTION TO ONCOLOGY

D – TERMINOLOGY DIFFICULTIES:

              Oncological terminology still presents some difficulties. However, in theory it obeys simple rules.  

              The name of a benign tumor generally ends with the suffix ( oma ), preceded by the radical defining the normal tissue that it is supposed to reproduce. The terms “ carcinoma ” and “ sarcoma” can also be used as suffixes for malignant tumors ( adenocarcinoma , chondrosarcoma ) when they are not used as nouns (   glandular carcinoma , chondroblastic sarcoma ) . The suffix “ blastoma ” is often applied to tumors whose embryonic structure recalls that of blastema tissue ( nephroblastoma , hepatoblastoma ).

              It is agreed that for a limited number of tumors whose architecture and origin are still poorly understood, until further information is available, we should stick to a provisional name, determined more by morphology and anatomy than by histogenesis: 

              Example :

• Alveolar soft tissue sarcoma ;
• Clear cell sarcoma of the tendon and fascia.

              Coordination and simplification efforts have been ongoing for several years, with the aim of perhaps one day achieving a clear, universal terminology with a universal coding system.

              Here are some of the most interesting attempts in this area:                      

• Illustrated nomenclature of tumors of the international union against      

      the concert (UICC 1965);

• Systematized nomenclature of medicine ( college of American      

      pathologists ) 1976;

• International Histological Classification of Tumors  

      from the World Health Organization ( WHO ). Published since 1967         

• International classification of diseases for oncology ( ICD-O ), world health organization 1976;

III – TUMOR, SWELLING AND CELLULAR PROLIFERATION:

              Contrary to what has been believed for centuries, many ” pathological swellings ” located in a part of the body are not tumors such as: abscesses, fracture calluses, hematomas, hemorrhoids, hydrarthrosis, hydroceles, edema nodules, etc.

              It is also recognized that ” cellular proliferation ” is not the histological prerogative of tumor tissue, just as the case of embryonic growth, although normal, is very reminiscent in several respects of that of cancer (accelerated cell cycle, mitoses, richness of cells in nucleic acids.

              Doctors have gradually learned to distinguish a proliferation of a neoplastic nature from a proliferation of another nature, however many obscure points persist.

              It should also be noted that each decade is marked by the individualization of a new tumor form or by the assertion that a lesion previously interpreted as cancer is in reality a non-neoplastic process, of an inflammatory, dystrophic or other type. Example: pseudo-sarcomatous modular fasciitis of the superficial aponeuroses .

              In truth, the difficulty is twofold, theoretical and practical. In principle, the exact nosological place of certain proliferative tissue alterations remains imprecise, particularly for benign tumors, due to the current insufficiency of etiopathogenic knowledge in oncology.

              In practice, the essential medical procedure consists in differentiating a cancer from a lesion that resembles it and is not malignant, since the therapeutic sanction depends on it: daily diagnostic experience plays a primordial role in this case. It is important that we insist on the following various points:

1 – tumor and inflammation:                                                                  

              Several abnormalities of the inflammatory process simulate the clinical, radiological, microscopic and even macroscopic appearance of a benign or malignant tumor:

              Example:

• Picture suggestive of bronchial carcinoma due to viral pneumonia;
• Intestinal transit disorders suggesting cancer when they are actually  

      result from ileocecal tuberculosis or diverticulitis 

      sigmoid;

              Histopathological identification of a similar picture does not usually encounter insurmountable obstacles because the analysis allows the recognition of either an obvious tumor or a more or less complex inflammatory or scleroinflammatory granuloma, with or without a necrotic area.

              However, histopathological identification can pose serious problems when inflammatory hyperplasia presents with mitoses, cellular abnormalities, and infiltration of normal structures.

              Finally, it should be noted that these anatomo-clinical confusions between tumor and inflammation have resulted in equivocal but still used expressions:

• ”  white tumor” designating tuberculous osteoarthritis. 
• ”  amoeboma” designating a massive sclerotic inflammatory

      hyperplastic and mortified of amoebic origin.

2 – tumor and hyperplasia:

              Discrimination is often difficult both with the naked eye and under a microscope.

              Various hyperplastic processes are diffuse , leading to an increase in the overall volume of a tissue or organ.

              Other hyperplastic processes are localized , forming deep parenchymal nodules called adenomatous or outgrowths on the surface of a glandular covering called polyploid. Both are accompanied by intense cellular proliferation. They may persist or undergo only a very slow involution after removal of the cause that provoked them and which often corresponds to an endocrine dysfunction. E xample:

• Diffuse or nodular prostatic glandular hyperplasia.
• Glandulocystic hyperplasia of the endometrium and diffuse or localized polypoid.
• Diffuse or modular thyroid hyperplasia (goiter).

3 – tumor and dystrophy:          

              They can simultaneously affect paired organs (breasts, ovaries) and involute when their cause disappears. But dystrophy is quite often revealed, clinically and radiologically, by poorly defined nodules simulating a tumor. Several dystrophies are also expressed, on microscopic examination, by intense hyperplasia with imprecise contours which also suggests a tumor process: E xample:

• Fibrocystic dystrophy of the breast
• Gynecomastia.

4 – relationship between tumor and pseudotumor:

              Many studies have shown that, with some exceptions, “ inflammatory tumors ”, “ hyperplastic tumors ” and “ dystrophic tumors ” which are in reality “ pseudo-tumors ” do not transform into cancer and should not be considered as a “precancerous lesion”. It can also be ensured that their presence does not promote the genesis of cancer in their vicinity.

              It is not uncommon for one or more inflammatory pseudotumors to be found around a cancer. They have the value of “ accompanying pseudotumors ” constituting a local reaction to the presence of the cancer and the inflammatory phenomena that they cause. E xample:

• Pseudopolyp located downstream of rectal cancer, laryngeal cancer 

      or maxillary sinus cancer.

• Uterine cervical pseudopolyp implanted downstream of a carcinoma of 

      the endometrium (called: “gatekeeper polyp”, “sentinel polyp”).

              The relatively frequent coexistence of breast cancer and fibrocystic dystrophy raises another problem: Breast carcinoma does not, in all likelihood, develop in a focus of fibrocystic mammary dystrophy, but both arise independently on an identical hormonal background of pituitary-ovarian deregulation primarily affecting progesterone secretion.

and lutheotropic hormone (LH).

INTRODUCTION TO ONCOLOGY

IV – PLACE OF PATHOLOGY (Pathological Anatomy and Cytology):

              The pathologist (anatomopathologist) certainly plays a role in fundamental and applied oncological research; and this role can be of the forefront.

              The role of the pathologist is also essential in oncological epidemiology because the value of statistics and cancer registries depends on the quality of anatomo-pathological data, as much if not more, than on the precision of knowledge on the evolution of the disease and on the patient’s living conditions.

              But the task of the pathologist in oncological practice is of a more immediate nature. It obviously involves him at all times in the life of the cancer.

• Daily cancer detection and diagnosis;
• Information provided to the surgeon by examination;
• Extemporaneous intraoperatively;
• Study of surgical excision parts;
• Post-therapeutic monitoring;
• Necropsy

              Far from isolating him within the confines of his laboratory, this task actively leads him, with clinicians, to assess the degree of tumor extension and to multidisciplinary pre- and post-therapeutic consultation. This task requires from the pathologist consummate experience in macroscopic and microscopic pathological anatomy as well as cytopathology.  

INTRODUCTION TO ONCOLOGY

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INTRODUCTION TO ONCOLOGY