Unfortunately, the cancer symptoms are not very specific. Many of the symptoms produced by cancer are shared by several other common ailments.
E.g. Pain in the upper abdomen, bloating, acidity, epigastric burning etc. could be due to gastritis, stomach ulcer, gallstones or due to stomach cancer also.
Similarly, difficulty in passing urine in an old individual is most commonly due to prostate enlargement. However even the cancer of the prostate presents itself in a similar manner.
Contrary to the examples above, an ulcerative growth in the mouth of an individual with a history of smoking or tobacco chewing is surely a cancer unless proved otherwise.
A lump in the breast of an old lady is considered cancerous unless proven otherwise.
Most of the internal organs cannot be evaluated completely by clinical examination alone. E.g. Liver, stomach, colon, lung etc. Hence it is difficult to diagnose cancer based purely on clinical examination., especially when the cancer is in early stages. However, cancers in the mouth, cervix and breast can be diagnosed with reasonable certainty as they can be examined thoroughly.
A tissue diagnosis is a must for the diagnosis of cancer. Tissue diagnosis means- confirming the presence of cancerous cells in the suspected lump/mass/ulcer by a pathologist with the help of a microscope. This requires obtaining a small chunk of tissue from the suspected cancerous growth by performing a biopsy. These small chunks of tissues are processed and made into thin slices mounted on glass slides. Then the pathologist sees these slides under a microscope and looks for cancerous cells to confirm or refute the diagnosis of cancer.
There are some cancers who have very typical features on CT and MRI scans. E.g. cancer of the liver (hepatocellular cancer), kidney cancer (renal cell carcinoma). Hence biopsy is not required when a surgical management is planned.
In case of testicular cancer, blood tumor markers help in confirming the diagnosis hence a testicular biopsy is rarely needed.
In pancreatic cancer, the imaging features are sufficiently suggestive of cancer and a biopsy of such a deep organ may actually give false negative results. Hence biopsy is not performed for pancreatic cancers.
A biopsy just tells us the presence of cancer, but not how far it has spread in the body. Hence several other tests are required to ascertain the exact extent of spread of cancer –inside the organ concerned, in the surrounding areas and to the distant parts. This evaluation is called staging evaluation as it determines the stage of the cancer. Only after a thorough staging evaluation the treatment can begin. This is because each stage of cancer has a specific type of treatment.
Three things are necessary to start treatment in cancer.
However, for internal organs like stomach, colon, rectum- biopsy can be obtained only by endoscopy.
1. Diagnosis of cancer : This requires a biopsy in most of the instances. For easily accessible organs like mouth, breast, cervix, limbs etc. a biopsy is an office procedure and does not require too much time and resources.
For organs like lung, liver, kidney, pancreas etc. biopsy can be obtained only with the help of a CT guidance.
Hence sometimes confirming a diagnosis requires preparation, time and other procedures.
2. Staging the cancer : to know where all it has spread.
A contrast enhanced CT scan / combined CT+PET scan are used frequently for this purpose.
Blood levels of tumor markers are estimated in most of the cancers.
3. Fitness of the patient :
In some instances, more than one imaging modality is used. E.g. for rectal cancers – MRI of the pelvis is used to map the local spread (as it is more sensitive than CT) and CT is used to map the spread in the rest of the abdomen and chest.
Cancer treatment can put considerable stress on the patient’s health. Hence, it is necessary to know that if a patient is fit enough to bear the cancer directed treatment.
This requires several tests-like- complete blood count, liver and kidney function tests, thyroid function tests, 2D ECHO (for heart function), Pulmonary function tests (for lung function).
Put together, a patient undergoes a considerable amount of tests before treatment begins. But it’s mandatory that proper evaluation is completed to ensure safety of the patient.