Principles of Cancer Classification	Ch 6
Ch...1 : General History Ch...2 : Prevention Ch...3 : Screening Ch...4 : Diagnosis Ch...5 : Tumor markers Select a chapter Ch...7 : Surgery Ch...8 : Radiotherapy Ch...9 : Chemotherapy Ch.10 : Hormonotherapy Ch.11 : New treatments Ch.12 : Multidisciplinarity Ch.13 : Psychology Ch.14 : Follow-up Ch.15 : Palliative care Ch.16 : Emergencies		Page 1 / 10

Why should we classify cancer tumours ?

The classification of the tumours has several goals :

• · Predicting prognosis,
  
• · Adapting therapy to the clinical situation,
  
• · Comparing therapeutic results between relatively homogeneous groups of patients,
  
• · Enabling therapeutic studies which are essential in proving any therapeutic progress.

Classification enables the definition of therapeutic groups, for which therapeutic protocols can be elaborated, taking into account all treatment possibilities.

It is essential for physicians to establish the classification of a tumour before any treatment can be administered to the patient in order to:

• · avoid proposing unnecessary treatment (for instance mutilating surgery when the patient unfortunately has metastases),
  
• · propose the most appropriate treatment (for instance: general treatment when localised treatment might be more appropriate).

Criteria used for tumour classifications

Very early in the twentieth century, physicians who exchanged data about their therapeutic results felt the necessity to base their common classification on objective, easy to understand and easy to implement factors.

Most classifications are based on clinical data. However, other criteria are sometimes considered.

The most determining factors are :

• the degree of local invasion,
  
• the degree of remote invasion,
  
• histological types of cancer with specific grading for each type of cancer,
  
• possibly various tumour markers,
  
• (in the near future, gene markers and other proteomic abnormalities may become determining factors),
  
• general status of the patient.

General methodology

A great number of consensus meetings were held among experts in order to set up classification standards.

The need for a common nomenclature led to the clinical classification of cancer by the League of Nations Health Organisation in 1929 and then by the UICC.

Just after the Second World War, Pr Pierre DENOIX (surgeon and Director of the Institut Gustave ROUSSY, near Paris), proposed to the UICC (International Union Against Cancer) Board, the TNM classification, which collects data from local tumour invasion (T), node invasion (N) and remote metastases invasion (M).

Other bodies (for example: AJCC: American Joint Committee on Cancer in 1959, FIGO: Fédération Internationale de Gynécologie et Obstétrique since 1937) proposed slightly different classifications and with time all classifications progressively converged towards an "improved TNM classification".

As the results of therapeutic studies progress according to these classifications, the classifications are improved, taking into account demonstrated prognostic factors. At regular intervals, in view of clinical and biological results, new modifications are discussed and accepted by UICC bodies.

These considerations explain the utmost importance of long-term clinical follow-up, which is the only way to verify classification value, the various proposed prognostic factors, the real impact of any new therapeutic measures on patient survival and the onset of late side-effects which could strongly modify the final result.

Result data collection enables a clear view of overall results and trends. In France, the Federation of Comprehensive Cancer Centres has collected therapeutic results for every patient treated in these hospitals for over 50 years. At an international level, the Fédération Internationale de Gynécologie et d'Obstétrique (FIGO) collects, every 2 to 3 years, the results of hundreds of clinical departments around the world.

The therapeutic protocol

The retrospective analysis of results enables the regular adjustment of cancer therapy and the definition of decision trees according to classification. At every stage, each therapy is motivated by observed results and complications. This clear protocol definition requires:

• · daily updating of literature knowledge,
  
• · great precision in the methodology of protocol drafting,
  
• · constant and rigorous application of the pre-defined protocol,
  
• · wide participation in clinical trials,
  
• · well organised follow-up of each patient,
  
• · voluntary, permanent and exhaustive collection, up-dating and presentation of therapeutic results.

In a subsequent chapter on multidisciplinarity, the importance in confronting the results and the experiences of various physicians and scientists from different specialities in order to elaborate efficient therapeutic protocols will be explained.

The following pages detail:

Staging assessment procedures

Histo-pathological classifications,

The main classification systems,

Several classifications and their prognostic value

General performance status classification