By Dr. Sandeep Nayak
In the beginning, the uncontrolled growth of cancer cells causes no pain. Pain starts only when the growth begins to affect nearby tissues that have pain sensors (receptors). Also in some cases, cancers secrete certain substances or trigger immune reactions that cause symptoms in other parts of the body that are not near to the cancer affected area.
The pain sensors are present abundantly only over some organs of the body. Most sensitive pain sensors are present in skin and bones. The other organs, especially bowel and soft tissues, do not have much sensors for pain. When a tumour is growing it can compress, irritate, block or destroy any tissue, tubes, ducts or blood vessels in the vicinity. Pain starts only when the cancer reaches the organs rich in these pain sensors or stimulates them by other means. When this happens nerves are stimulated and a flow of information travels along nerve pathways up to the brain where pain is perceived.
Cancer pain may correspond directly to the spot where the tumour is located, or to a distance from the original source, what is called referred pain. But pain is noteworthy, whether it is slight or strong and needs to be investigated thoroughly.
The quality and quantity of cancer pain also depends on how much room there is for the tumour to expand. So if a tumour is hemmed in the brain, pain might be experienced sooner than tumours in the belly, where it has more space to grow and spread.
When any lump or swelling is growing painlessly, the very absence of pain should make you consider cancer. Consult your doctor as soon as symptoms start.