Every year on the first Sunday of June, the world celebrates cancer survivors. And it should. The fact that a cancer diagnosis is no longer the automatic death sentence it was in 1988, when the first National Cancer Survivors Day was held, is one of medicine’s genuine triumphs (1). Survival rates have climbed. Treatments have improved. Lives have been extended.

The Real Question For Survivors

As we celebrate survival, an important question remains: how can we best support people as they move beyond cancer treatment? Finishing treatment is a major milestone, but it is not always the end of the health challenges that follow.

Many individuals reach the end of treatment having navigated physical, emotional, financial, and social challenges that few people can fully appreciate. The purpose of this conversation is not to suggest that anyone is responsible for their illness or recovery, but rather to highlight an often-overlooked aspect of long-term health that may deserve greater attention.

Because finishing treatment is not the same as reclaiming metabolic health. For millions, metabolic disturbances that may have been present before diagnosis, or developed during treatment, remain very much present on the other side of the clinic door (2,3).

It is well-established that chemotherapy and radiation save lives. Less discussed is what they do to the body’s metabolic machinery. Research suggests that treatment can molecularly rewire skeletal muscle, which is responsible for over 80% of glucose uptake from the blood in response to insulin, leaving survivors with insulin resistance that was induced, not inherited (4). In women with breast cancer specifically, metabolic disorders post-treatment are associated with an 83% increase in mortality and up to a 69% increase in recurrence risk (5). These are not marginal numbers. And insulin resistance is not merely a diabetes precursor. It is a pro-inflammatory, pro-tumorigenic state. High levels of insulin in the blood trigger growth signals that make cancer cells multiply faster and prevent the body from destroying them the way it normally would (6). A 2026 study using an AI-based screening tool found that insulin resistance was associated with a 25% higher risk across 12 distinct cancer types (7). For a cancer survivor, this is not background noise. It is a modifiable risk sitting at the centre of their biology.

Most cancer cells are almost entirely glucose-dependent, requiring up to 30 times more glucose than healthy cells (8). This is why lowering circulating glucose and insulin has biological plausibility for cancer prevention and treatment. When carbohydrate availability drops, healthy cells adapt by using fats and ketones for fuel. Most cancer cells cannot make that switch. A body of research identifies four interrelated pathways through which carbohydrate restriction may affect tumour biology: lowering glucose and insulin, altering mitochondrial dynamics, reducing inflammation, and downregulating mTOR and IGF-1 signalling, all directly relevant to recurrence risk and treatment response (6).

We want to be clear: the human clinical evidence for ketogenic or LCHF diets as cancer therapy is promising but still maturing. Most robust data comes from preclinical models and smaller trials. Large randomised controlled trials in survivorship populations are still underway. This is not a prescription.

The Case for Metabolic Health

What the evidence does support is this: insulin resistance is a modifiable risk factor with direct biological relevance to cancer recurrence and mortality. Dietary carbohydrate restriction is one of the most effective tools we have for lowering fasting insulin, reducing visceral adiposity, and improving the metabolic environment (9). While nutrition is only one component of survivorship care, it is one of the few factors that survivors may be able to influence directly, often alongside physical activity, sleep, stress management, and appropriate medical follow-up.

Many aspects of survivorship care rightly focus on recurrence monitoring and ongoing treatment effects. Yet metabolic health is often discussed less frequently, despite growing evidence that it may influence long-term outcomes and overall well-being.

In South Africa, the metabolic disease burden and the cancer burden do not sit in separate silos (11). They overlap in the same communities, the same households, the same bodies. Access to both oncological surveillance and good food is unequal. But the Eat Better South Africa framework, centred on real whole foods and the reduction of refined carbohydrates and seed oils, is one of the most accessible and affordable metabolic interventions available. That is not incidental to this conversation. It is the reason this foundation exists.

Improving metabolic health after cancer is not always straightforward. Treatment can affect appetite, body composition, energy levels, and physical function, while access to nutritious food remains a challenge for many South Africans. The goal is not perfection, but identifying practical steps that may support long-term health alongside ongoing medical care. 

If you are a cancer survivor or care for one, ask your oncologist or GP about metabolic screening post-treatment. Ask about fasting insulin, HOMA-IR, and your triglyceride-to-HDL ratio, not just whether the cancer is “clear.” These markers tell you something important about the terrain your body is living in.

If metabolic health has not been part of the conversation, consider asking further questions and discussing the emerging evidence with your healthcare team.

Surviving cancer is extraordinary. Supporting long-term metabolic health may be one way to help more survivors live not only longer, but better.

References

1.     Siegel, R. L., et al. (2026). Cancer statistics, 2026. CA: A Cancer Journal for Clinicians, 76(1), 10–41. https://doi.org/10.3322/caac.70043
2.     Alshahrani, S., et al. (2024). Insulin resistance: The increased risk of cancers. PMC, PMC10888119. https://pmc.ncbi.nlm.nih.gov/articles/PMC10888119/
3.     Häring, H.-U., et al. (2007). Prospective study of hyperglycemia and cancer risk. Diabetes Care, 30(3), 561–567. https://doi.org/10.2337/dc06-0922
4.     Merz, K. E., & Thurmond, D. C. (2020). Role of Skeletal Muscle in Insulin Resistance and Glucose Uptake. Comprehensive Physiology, 10(3), 785–809. https://doi.org/10.1002/cphy.c190029
5.     Harborg, S., Larsen, H. B., Elsgaard, S., & Borgquist, S. (2025). Metabolic syndrome is associated with breast cancer mortality: A systematic review and meta-analysis. Journal of Internal Medicine, 297, 262–275. https://doi.org/10.1111/joim.20047
6.     Bowers, L. W., Rossi, E. L., O’Flanagan, C. H., deGraffenried, L. A., & Hursting, S. D. (2015). The Role of the Insulin/IGF System in Cancer: Lessons Learned from Clinical Trials and the Energy Balance-Cancer Link. Frontiers in endocrinology, 6, 77. https://doi.org/10.3389/fendo.2015.00077
7.     Hiraike, Y., Lee, C.-L., Kondo, T., Terasawa, K., Kizuka, M., Kinoshita, A., Oka, S., Ito, C., Ito, H., & Hiraike, K. (2026). Machine learning-predicted insulin resistance is a risk factor for 12 types of cancer. Nature Communications, 17, Article 1683. https://doi.org/10.1038/s41467-026-68355-x
8.     DeBerardinis, R. J., & Chandel, N. S. (2016). We need to talk about the Warburg effect. Nature Metabolism, 8(2), 127–129. https://doi.org/10.1038/s41591-021-01264-5
9. Yancy, W. S., Jr, Foy, M., Race, A. M., & Westman, E. C. (2004). A lower-carbohydrate, higher-fat diet reduces abdominal and intermuscular fat and increases insulin sensitivity in adults at risk of type 2 diabetes. Journal of Nutrition, 134(1), 241–246. https://doi.org/10.1093/jn/134.1.241
10. Schlesinger, S., Nagel, G., & Schulze, M. B. (2020). Diabetes and cancer: A systematic review of epidemiological evidence. Diabetologia, 63(5), 895–907. https://doi.org/10.1007/s00125-020-05091-8