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Cancer diagnosis always requires a biopsy and a pathological examination (except during terminal phases when therapy is not feasible).

Except in such rare situations, beginning radical treatment without the histological (or at least cytological) proof of malignancy would be verging on malpractice. Some long lasting infections, certain benign tumours and a few rare diseases may mimic cancer; however the erroneous administration of radiotherapy or chemotherapy in such circumstances would be a source of major complications.

In order to ensure a genuine multidisciplinary discussion and concerted therapy decision integrating and combining all available therapeutic facilities (peroperatory radiotherapy, preoperatory chemotherapy), it is essential to try to obtain histological certainty before any operation.

Exploratory laparotomies (”to see what’s going on”) should become an exception in the case of convergent diagnostic arguments (avoiding the multiplication of unnecessary paramedical examinations). Since it is an aggressive act for the patient, it should only be proposed after thorough consideration and preoperative patient preparation in order to perform, in one single operation, both diagnosis and therapy.rapy.

Pathology techniques

With the courtesy of Dr Yves DENOUX, a previous pathologist at the Centre François Baclesse, we have described the various techniques used for pathological diagnosis.

Medical students who have never had the opportunity of practical work experience in a pathology unit may find useful information to improve their understanding of histological reports, throughout the following pages.

- standard techniques for pathology

- specific staining techniques,

- cytology techniques,

- extemporaneous examinations,

- immunohistochemistry techniques,

- in situ hybridation techniques,

- PCR technique (polymerase chain reaction),

- cytometry techniques

Cytology

Many cancer types produce fluid extravasation which can be studied by a cytology technique: pleural effusion and ascites, cerebrospinal fluid.

Normal cytology	Cancer cytology

Preoperative biopsies

Recent clinical progress has resulted in more and more frequent preoperative histological diagnosis with the use of endoscopies which detect the tumour and enable accurate biopsies. Similarly, new interventional radiology techniques enable needle biopsies. A few examples:

• laryngoscopy and biopsies for head and neck tumours,
  
• bronchoscopy for lung tumours,
  
• gastrocopy for gastric tumours,
  
• colonoscopy, rectoscopy for rectocolic tumours,
  
• colposcopy and hystéroscopy for uterine tumours,
  
• cystoscopy for bladder and prostate tumours,
  
• ultrasonography guided biopsies for mammary, liver, renal, prostatic and other tumours,
  
• stereotaxic guiding for biopsy of mammary tumours.

Operation specimen

For certain tumours, the biopsy approach should be postponed due to the risk of dissemination to the adjacent wall, and a well defined surgical act should be proposed as soon as the probable diagnosis has been seriously contemplated: soft tissue sarcoma, peritoneal carcinomatosis due to ovarian carcinoma or testis tumour, for instance.

The macroscopic study of surgical specimens should:

• describe with full detail the various specimen sent by the surgeon
  
• describe the general macroscopic aspect (size, colour, physical aspect)
  
• specify the surgical limits,
  
• detect nodes and prepare systematic slices for histology,
  
• prepare serial and/or well oriented slices with a clear individualisation of the surgical limits.

Extemporaneous examination

For many tumours, diagnosis of malignancy may remain uncertain until radical surgery.

For instance, breast carcinoma may often present as a very suspicious but small sized image, the exeresis of which should be performed allowing for healthy limits.

For thyroid carcinoma, the arguments in favour of cancer are more or less clear and a peroperative pathological confirmation is often useful.

Studying the limits of soft tissue sarcoma by an extemporaneous examination has been shown to increase the number of complete excisions and therefore to obtain a better clinical result.

Such extemporaneous examinations are technically very difficult: the pathologist should be given sufficient time to thoroughly study the specimens.

More and more frequently, tumour specimens are simultaneously conserved in liquid nitrogen for specific studies (markers, oncogenes, in situ hibridisation, abnormal protein studies) as part of tissue banks common to Cancer Centres. The precise correlation between clinical evolution (hence the necessity for a global medical record) and tissue characteristics will allow major studies on prognostic factors and will modify therapeutic schemes.

In the same manner, it may be useful to use part of the tumour specimen for tissue culture of cancer cells thus enabling specific metabolic studies. The proximity of research laboratories and operating theatres is mandatory for such studies. The study of freshly cultivated cells (primary culture) avoids the use of long-term cultivated cell lines having lost their physiological or pathological clinical characteristics.

Microscopic study

Microscopic study should:

• identify the histological tumour type,
  
• propose a differentiation study according to established grading system,
  
• precise the exeresis limits of the tumour,
  
• identify the invasion status of the sampled nodes, particularly capsular disruptions.