The immune system plays a crucial role in identifying and eliminating abnormal cells, including cancer cells. However, cancer cells can develop mechanisms to evade the immune system’s surveillance and attack, allowing them to proliferate and form tumors.

Following are some key points describing the relationship between cancer and the immune system:

1. Immune Surveillance: There is constant patrolling inside the body by immune system for any cells that display abnormal characteristics, such as those found in cancer. Immune cells like T cells and natural killer (NK) cells can recognize and eliminate these abnormal cells.

2. Tumor Antigens: Unique molecules / antigens that are not present on normal cell are often produced by cancer cells. These antigens can be recognized by immune cells, particularly T cells, as signals of potential threats.

3. Immune Response: When immune cells recognize these cancer cells as foreign or abnormal, they initiate an immune response. T cells can directly attack on these cancer cells, while other immune cells start releasing signaling molecules (cytokines) that attract more immune cells to the site of the tumor.

4. Immune Evasion: Cancer cells can develop various strategies to overcome immune detection and destruction. For example, they might downregulate the expression of certain antigens, inhibit immune cell activity, or even express molecules that induce immune tolerance.

5. Cancer and Inflammation: Chronic inflammation can also increase the risk of cancer development. Certain immune responses, especially chronic in nature can lead to tissue damage and mutations which may lead to cancer initiation and This is why conditions associated with chronic inflammation, such as inflammatory bowel disease, are linked to an increased cancer risk.

Definition: Cancer is a group of diseases which is  characterized by the uncontrolled growth and spread of abnormal cells in the body. The signs and symptoms of cancer can vary  depending on the type of , location, and stage of cancer. Here are some common signs and symptoms that might indicate the presence of cancer :

1. Unexplained and Significant Weight Loss : If there is a noticeable and unexplained weight loss in a person, this can be sign and symptom of cancer.

2. Persistent or increasing pain : Persistent/ increasing pain, if it’s localized and doesn’t have an obvious cause, could be a symptom of certain types of cancer.

3. Fatigue or Weakness : Tiredness or Fatigue or weakness which is persistent and even does not get better on taking rest can be sign of cancer.

4. Lumps or masses : Noticeable lumps or masses under the skin might be indicative of various types of cancer.

5. Changes in the Skin: If there is a change in the color, size, shape, or texture of a mole or other skin lesions might indicate skin cancer.

6. Difficulty Swallowing: Trouble swallowing or persistent hoarseness might be sign and symptom of throat or esophageal cancer.

7. Persistent Cough: A chronic cough or hoarseness that doesn’t go away after taking medical help or treatment could be a sign of lung or throat cancer.

8. Fever : Having recurrent and unexplained fever might indicate a possibility of cancer affecting immune system.

9. Changes in Mouth : Unhealing ulcers and white or red patches on the gums, tongue, tonsils, or lining of the mouth could be signs of oral cancer.

10. Changes in Bowel or bladder habits : Persistent changes in bowel habits (diarrhea, constipation) or urinary habits (blood in urine, increased frequency) might be indicative of certain types of cancer.

11. Changes in Breast Appearance: Changes in the size, shape, or appearance of the breast, and nipple changes, might be signs of breast cancer.

Unexplained Bleeding: Unexplained bleeding, such as blood in the stool, urine, or appearance of blood in cough or sputum, could be a symptom of various cancers.