Laboratory

Histopathology	Cytology	Biochemistry
Microbiology	Clinical Pathology	Instruments

The laboratory plays a central role in diagnosing cancer. Although patient’s vigilance and the clinician’s alertness are the primary ways in detecting early onset of the disease, it is the laboratory which confirms its presence. Then, during treatment the patient’s condition is monitored by various laboratory tests.

Can cancer be diagnosed by testing blood? This is an often heard question. The answer to which is that, yes, few cancers like leukemia can indeed be diagnosed by examining blood. However, a vast majority of the cancers originating in visceral organs and skin leak cancer cells into blood only after the cancer is well advanced and reaches terminal stages. Therefore, many cancers cannot be diagnosed by examining blood only.

Does biochemical testing of blood for tumor markers detect cancer? Yes, certain cancers like prostate cancer, liver cancer and some gastrointestinal cancers secrete specific markers that can be detected in blood or other body fluids. However, again there are many more cancers that do not secrete any currently detectable markers.

How does biopsy help in detecting cancer? Normal cells transform to cancer cells due to complex genetic damage brought about by various carcinogens. The transformed cells may resemble the cells of the tissue of origin or be completely different. The transformed cells may retain normal function, become functionless or acquire new function. In suspected cases, tissue is obtained by excising (biopsy) it and studying its morphological features. This histological examination is the best method to identify the transformed malignant (cancer) cells.

Histopathology

It is important to know the nature and stage of the cancer to effectively treat it. Histopathological examination is the single most important test to tell us about the nature of the cancer and its aggressiveness. Specific parameters like the tumor’s differentiation, mitotic rate and spread into neighboring tissue or distant organs are established by this test. In instances where the differentiation could not be made out by routine histopathological examination, special stains and immunohistochemical stains are performed. Rarely, electron microscopy is employed to aid the identification of the cancer. Occasionally, in spite of the different methods employed, a cancer may elude classification. Another aspect of this test is the accuracy of the biopsy. Occasionally the biopsy tissue submitted may not be representative of the diseased focus. In such instances the diagnosis may be missed and a false negative report given. Despite these intricacies, histopathological examination has emerged as the ultimate diagnostic test for cancer.

Cytology

Biopsy, because of its invasive nature, and sometimes because of deep location of the lesion, may not be the first test of choice. Fine needle aspiration (FNA), is then used to obtain cells from the lesion. This procedure could be either done by the examining Physician or the Pathologist on superficial lesions, but may require the Radiologist’s help by Ultrasound or CT guidance. The cells obtained by FNA are then examined for presence of cancerous change. An FNAC diagnosis has more value when it is positive. In the case of female genital tract cytological examination has become a very popular screening test i.e. PAP test.

Biochemistry

In certain cancers, the tumors secrete specific substances called tumor markers Elisa based laboratory tests are used to detect the presence or increase in the levels of these markers The patients’ blood, urine or other body fluids are examined for detecting their presence. Although these markers are altered in states of cancer, they are not very specific. Hence these tests are used as ancillary or adjuncts to other tests or clinical history in diagnosis of cancer. The utility of the markers lies more in the follow-up, where any recurrence or metastases remaining behind after excising the main tumor can be detected. During treatment of cancer, the patients may be subjected to radiation, chemotherapeutic drugs or surgery. The general condition of the patient and the status of other body systems are evaluated before launching the treatment. The biochemical test provides the objective parameters of the well being of organs like liver and kidney. A basal level of functioning of these organs before commencement of treatment is established by these tests.

Microbiology

During treatment, if the patient is immuno suppressed, infections can supervene. Such patients are monitored by performing a culture of the material obtained from suspected site. Special stains can be performed to detect the microorganisms. The patients blood can be examined for antibodies to know microorganisms. This provides indirect evidence of infection. As is well known, infections by Hepatitis B and C, HIV, HPV, viruses can in chronic conditions lead to development of cancers

Clinical Pathology

Routine examination of blood and body fluids is an integral part of testing for cancer patients. Anemia and bleeding problems may arise due to the effect of cancer or its treatment. The need for giving iron or vitamin supplementation or Erythropoietin to treat anemia can be assessed by specific laboratory testing. This helps in correcting specific deficiency. Body fluids are sometimes examined to detect spread of cancer to body cavities.

Recent advances in laboratory medicine like Fluorescent Activated Cell Sorting (FACS), Polymerase Chain Reaction (PCR), Fluorescent in-situ hybridization (FISH) provide higher specificity and sensitivity. These tests can be employed for initial diagnosis as well as detecting any relapse of cancer. However, these tests are costly and not used for routine diagnosis.

A wide variety of tools are provided by the laboratory which aid in screening, diagnosis and monitoring of patients during treatment. An expert clinician employs these resources to detect and accurately diagnose cancer in early stages. Once the diagnosis is made, the laboratory again helps to monitor the patient for the treatment and relapse in unfortunate cases.

Instruments

• Dade Automatic Analyzer: This is the fully automated chemistry analyzer that can process more then 50 samples at a time. Complete automation removes scope for technical errors and gives the high reproducibility and accuracy. Besides routine biochemical tests, drug assays and immunological markers can also be tested.
  
• Coulter: This is 18 parameter read out automated coulter. Besides routine hemoglobin, blood cells counts, Hemocrit, it also does three part differential.
  a) This instrument is very useful in rapid coating of blood count of multiple patients with high accuracy.
  
• Elisa PlateReader: This is automated instrument of giving rapid estimation of concentration in various tests like tumor markers, infection diseases like hepatitis, AIDS as instrument can read 96 wells at a time multiple patients can be simultaneously read out. The attached computer stores data which can be further analyzed over a period of time.
  
• Electrolyte Analyzer: This is automated electrolyte based analyzer that can rapidly measure the concentration of electrolyte like NA, K and chlorides, fluorine. Because of automation nature very high accurate results are obtained.