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Cancer can affect your body in several ways, causing the most common to rarest symptoms. One of the early indicators can be frequent infections, a doctor notes. Here’s what to watch out for.

Cancer is an umbrella term for a group of diseases that are characterised by abnormal cell growth and its potential spread to other parts of the body. Cancer isn't a single disease but rather a group of more than 100 diseases that affect different organs and functions in the body.

According to the World Health Organization (WHO)’s cancer agency, the International Agency for Research on Cancer (IARC), in 2022, there were an estimated two crore new cancer cases and 90.7 lakh deaths. About 1 in 5 people develop cancer in their lifetime; approximately 1 in 9 men and 1 in 12 women die from the disease.

As per the IARC’s Global Cancer Observatory, 10 types of cancer collectively comprised around two-thirds of new cases and deaths globally in 2022. Lung cancer was the most commonly occurring cancer worldwide, with 20.5 lakh new cases, accounting for 12.4% of the total new cases. Female breast cancer ranked second (20.3 lakh cases, 11.6%), followed by colorectal cancer (10.9 lakh cases, 9.6%), prostate cancer (10.5 lakh cases, 7.3%), and stomach cancer (9.7 lakh cases, 4.9%).

Cancer affects the body by disrupting normal cell growth, leading to uncontrolled cell division and the formation of tumours that can damage healthy tissues. Cancer cells can also spread to other parts of the body through the bloodstream or lymphatic system, causing further damage and potentially affecting multiple organs.

"From an oncological standpoint, several nonspecific symptoms should prompt evaluation if persistent or unexplained," highlights Dr Sarin. These include:

“While these symptoms don’t confirm cancer, their presence, especially in combination with frequent infections, should lead to timely medical evaluation. Early detection significantly improves treatment outcomes in most cancers,” he adds.

Interestingly, frequent infections can occasionally be an early indicator of certain cancers, particularly haematological malignancies such as leukaemia, lymphoma, or multiple myeloma, shares Dr Sarin, adding that these cancers originate in the blood or lymphatic system and can compromise the body's ability to produce functional immune cells.

"When normal White Blood Cell (WBC) function is disrupted, the body’s ability to fight infection diminishes, which may manifest as recurrent or unusually severe infections," he explains.

In some cancers, particularly those affecting the bone marrow or lymphatic system, the immune system is directly compromised. For example, in leukaemia, malignant cells proliferate in the bone marrow and crowd out healthy white blood cells, impairing the immune response. Additionally, cancers can produce substances that suppress immune activity, and treatments such as chemotherapy, radiation, and immunosuppressive therapies further reduce immune competence.

This weakened state predisposes patients to both common and opportunistic infections.

Patients with undiagnosed cancer, especially haematologic cancers, may present with infections that are frequent, persistent, or resistant to conventional treatment. Common examples include:

• Skin or soft tissue infections
• Sinus or ear infections

Opportunistic infections that are otherwise rare in healthy individuals can also occur and should raise suspicion of an underlying immunocompromised state.

If you have persistent or recurrent fevers, sore throats, or respiratory infections, especially when unexplained or poorly responsive to treatment, it may warrant further investigation. “As an oncologist, I would recommend a Complete Blood Count (CBC) with a differential as an initial step,” advises Dr Sarin. He adds that any abnormalities, such as unexplained anaemia, leukopenia, or thrombocytopenia, should prompt further diagnostic workup, including imaging or bone marrow evaluation, depending on the clinical picture.

The key is not to ignore patterns; recurrent infections in an otherwise healthy adult should never be dismissed, the doctor concluded.