Kidney cancer is the 14th most common cancer worldwide and remains among the leading cancers affecting both men and women. According to the World Cancer Research Fund, there were an estimated over 4.34 lakh new cases of kidney cancer globally in 2022.
While established risk factors such as smoking, hypertension, and obesity have long been linked to kidney cancer, researchers are now increasingly examining whether the roots of the disease may begin much earlier in life. Emerging evidence suggests that excess body weight during childhood and adolescence may have long-term effects that extend well beyond metabolic health and could influence the risk of developing kidney cancer decades later.
Adding to this growing body of research, a 2025 study using data from public genome-wide association study (GWAS) databases found evidence supporting a causal association between obesity in early life and kidney cancer incidence. The researchers analysed birth weight and body mass index (BMI) across childhood, adolescence, and adulthood and found that childhood obesity, higher childhood BMI, adolescent BMI, and adult BMI were all significantly associated with an increased risk of kidney cancer and its most common subtype, clear cell renal cell carcinoma (ccRCC). The study also found no evidence of reverse causation, suggesting that excess weight may play a direct role in increasing cancer risk.
The findings raise important questions about whether maintaining a healthy weight from an early age could help lower the risk of kidney cancer later in life. On the occasion of World Kidney Cancer Day, we spoke to Dr Sneha Kommineni, Consultant - Medical Oncology, Aster RV Hospital to understand how obesity during childhood and adolescence may affect kidney health, why excess body fat can influence cancer development and what steps individuals can take to reduce their long-term risk.
Childhood obesity may have consequences beyond diabetes and heart disease
Dr Sneha Kommineni, Consultant - Medical Oncology, Aster RV Hospital, said that childhood obesity has traditionally been linked to conditions such as diabetes, hypertension, and cardiovascular disease. However, emerging evidence suggests that its effects may extend much further, potentially influencing the risk of certain cancers later in life, including kidney cancer.
"Researchers are increasingly asking whether the origins of some cancers may lie much earlier than we previously assumed. Kidney cancer, particularly renal cell carcinoma, is one area where this question is being explored," she said.
Dr Kommineni explained that the kidneys are highly vascular organs that continuously filter blood and regulate several essential functions. Excess body fat can affect these organs through multiple biological pathways.
"Obesity is associated with chronic low-grade inflammation that can persist for years. Over time, this inflammatory environment may damage tissues and create conditions that favour the growth of abnormal cells," she said.
She added that obesity is also linked to insulin resistance and elevated levels of insulin-like growth factors, which may stimulate cell growth and interfere with the body's ability to eliminate damaged cells.
"Another important mechanism is oxidative stress. Excess fat can increase the production of reactive oxygen species, which may damage cellular DNA. Such DNA damage is considered an important step in the development of several cancers, including kidney cancer," she explained.
Duration of obesity may matter as much as severity
Dr Kommineni noted that recent research suggests the length of time a person remains overweight may be as important as the degree of obesity itself.
"A child who develops obesity at a young age may be exposed to metabolic stress, hormonal disturbances, and chronic inflammation for decades. Researchers refer to this as cumulative exposure. The longer the exposure to these biological changes, the greater the potential impact on disease risk," she said.
She added that because kidney cancer often develops silently and is usually diagnosed in middle or older age, the disease process may begin many years before symptoms appear.
Can weight loss help lower the risk?
While studies are still evaluating whether weight loss can completely reverse cancer risk, Dr Kommineni said obesity remains a modifiable risk factor.
"There is strong evidence that improving metabolic health can reduce inflammation, improve insulin sensitivity, and lower the burden of several obesity-related diseases," she said.
According to her, adopting healthier lifestyles during childhood and adolescence - including maintaining a healthy weight, staying physically active, and following balanced dietary habits - may help reduce some of the long-term health consequences associated with obesity.
"No single intervention can guarantee cancer prevention, but improving overall metabolic health remains one of the most effective strategies available," she added.
The growing relevance for India
Dr Kommineni pointed out that the issue is particularly relevant in India, where obesity among children and adolescents has been steadily rising.
"Increasing screen time, reduced physical activity, and greater consumption of calorie-dense processed foods have contributed to a growing obesity burden among younger populations," she said.
She added that doctors are also witnessing metabolic disorders such as diabetes and hypertension appearing at younger ages. Since these conditions share several biological pathways with obesity-related cancers, understanding the long-term impact of excess weight has become increasingly important.
She stressed that obesity should not be treated only as a childhood problem or merely as a cosmetic concern. "It is increasingly recognised as a condition that can affect multiple organ systems over the years," she said. "The message is not that every child with obesity will develop kidney cancer, as the absolute risk remains relatively low. However, childhood health can shape disease risk decades later. Promoting healthy eating habits, regular physical activity, adequate sleep, and routine health check-ups from an early age may help reduce the risk of metabolic disorders and potentially some cancers later in life."
This story is done in collaboration with First Check, which is the health journalism vertical of DataLEADS
