Weight Loss Works During Prostate Cancer Surveillance, But Feeling Better Is Not Guaranteed

Men diagnosed with low-risk prostate cancer increasingly face a choice that sounds simple but is anything but: undergo immediate treatment, or enter active surveillance and live with the knowledge that a cancer is sitting inside them, being watched rather than attacked. For the growing number of men who choose surveillance, a natural question follows close behind the diagnosis. If I eat better and exercise more, will I actually feel better? A new editorial published in Supportive Care in Cancer by Matthias May of St. Elisabeth Hospital Straubing and colleagues takes a hard, quantitative look at that question, and the answer they arrive at is a sobering lesson in the difference between achieving a measurable clinical goal and delivering the subjective benefit patients hope for.

The trigger for the editorial is a secondary analysis from the Prostate Cancer Active Lifestyle Study, known as PALS, reported by Zhu and colleagues in the same journal. PALS randomized 117 men with overweight or obesity who were on active surveillance for prostate cancer to an intensive six-month dietary and exercise intervention adapted from the well-known Diabetes Prevention Program, or to a control condition consisting of a single counseling session with a study dietitian reviewing standard US dietary and physical activity guidelines. The intervention combined dietary counseling with individualized exercise instruction, heart-rate targets, and opportunities for supervised activity. On the primary front, the program worked impressively: men in the intervention arm lost an average of 7.1 percent of their body weight over six months, compared with just 1.8 percent among controls. That is a clinically meaningful difference by any standard of weight management research.

Yet when the researchers turned to health-related quality of life, the picture changed dramatically. The six-month dietary and exercise intervention did not demonstrate broad improvement in how the men felt, functioned, or experienced symptoms. Quality of life had been prespecified as a secondary outcome, while the trial’s sample size calculation was built around changes in glucose-regulation biomarkers, meaning the study was never powered to detect subtle quality-of-life differences in the first place. A complete-case analysis, with 99 of the original 117 men contributing to the six-month quality-of-life assessment, adds further uncertainty. Isolated item-level findings and exploratory subgroup results, obtained without adjustment for multiple statistical comparisons, cannot establish which patients, if any, are more likely to feel better on this program. The editorial’s central warning follows directly from this: weight reduction, improved physical capacity, symptom relief, and cancer control are distinct clinical objectives, and evidence for one should never be used to promise another.

The broader trial landscape reinforces that caution. In the Prostate Cancer Lifestyle Trial, comprehensive changes in diet, exercise, and stress management failed to produce significant between-group differences in quality of life at one year, and the favorable associations observed between achieved behavior change and quality of life within that study were observational rather than causal. In the Men’s Eating and Living trial, simply increasing vegetable intake produced no additional quality-of-life benefit over 24 months, although the authors of that study noted that baseline scores among participants were generally high, leaving little room for measurable improvement. The editorial is careful to note that high starting scores plausibly limit detectable benefit but should not become a universal explanation for every null result, and that these longer trials caution against assuming duration alone explains the PALS findings.

Exercise-focused trials tell a more nuanced story. In the ERASE trial, 52 men on active surveillance were randomized to supervised high-intensity interval training or usual care for 12 weeks. Training reduced total prostate cancer-specific anxiety on the Memorial Anxiety Scale for Prostate Cancer by an adjusted 2.7 points relative to controls, and the fear-of-progression subscale improved, though two other measures of cancer-related fear showed no significant differences. The estimated global quality-of-life difference was 6.8 points on a 0-to-100 scale, but the confidence interval spanned from minus 0.4 to 13.9, an interval that permits a worthwhile benefit without establishing one. In the Active Surveillance Exercise trial, 51 men with low or moderate fitness were randomized to a tailored home walking program with heart-rate monitoring and weekly calls from an exercise physiologist, or to printed activity advice. After 16 weeks, cardiorespiratory fitness improved, with additional signals for less urinary irritation and less cancer-related fear, while general physical and mental health scores showed no significant between-group differences. A 2024 meta-analysis found improved cardiorespiratory fitness across trials, with an uncertain pooled quality-of-life effect of 0.24 standardized mean difference units, though a sensitivity analysis excluding the Prostate Cancer Lifestyle Trial yielded a statistically significant effect of 0.38 favoring intervention.

What emerges from this patchwork, the editorial argues, is that delivery details matter enormously. Neither PALS nor the exercise trials support treating the choice as a simple binary between supervised exercise and unsupported advice. The important variables are the specific exercise prescription, the support provided, and the dose of exercise participants actually complete. Each trial evaluates a package of exercise and support, and comparisons across trials cannot isolate which component accounts for differing results. This has direct practical consequences for the growing population of men on surveillance, who often chose that path precisely to limit disruption to their daily lives and may be unwilling or unable to sustain demanding programs without accessible professional follow-up.

The editorial also draws a sharp contrast with the evidence from men undergoing active treatment. During androgen deprivation therapy, exercise and lifestyle interventions address a burden imposed by the treatment itself. The recent STAMINA trial, involving 700 men receiving androgen deprivation therapy, demonstrated that an integrated exercise and dietary intervention mitigated deterioration in cancer-specific quality of life, and the European Association of Urology recommends supervised combined aerobic and resistance exercise specifically for men on ADT. Whether comparable benefits can be achieved during active surveillance, in the absence of treatment-related toxicity, remains to be demonstrated. For men on surveillance, the editorial insists, the rationale for exercise should be stated in terms of their own symptoms, function, and health risks, not borrowed from the treatment-toxicity literature.

Equity and adherence concerns add another layer of complexity. In PALS, eight of 58 intervention participants and nine of 59 controls did not complete the trial. Notably, the intervention noncompleters included four of the five Black men randomized to that arm, and all eight noncompleters were in the lowest reported education category. The editorial is careful about what these observations do and do not show: they warrant investigation of barriers to sustained participation but do not establish why men withdrew or whether missing outcomes biased the estimates. Future studies, the authors argue, should report reasons for withdrawal and test whether conclusions hold under plausible assumptions about missing data, a methodological standard that remains rare in lifestyle oncology research.

The practical prescription that emerges is one of goal-matched care. At a surveillance visit, clinician and patient should agree on a specific goal for lifestyle care, whether that is weight loss, improved fitness, relief from fatigue, or management of anxiety, and decide in advance how progress toward that goal will be measured. Body mass index identifies a population in whom weight management may be appropriate, but it does not identify the symptom or functional limitation most likely to respond. A man troubled by fatigue, one with poor aerobic capacity, and one with substantial metabolic risk may need different prescriptions and different measures of success. For research, the editorial calls for trials that define the intended benefit and target population before selecting the intervention, dose, and primary outcome, with prespecified and adequately powered interaction analyses when differential response is the question, and with appropriate oncologic outcomes whenever cancer-control claims are made, since changes in weight or metabolic biomarkers cannot substitute for them.

The bottom line is a recalibration of expectations rather than a rejection of lifestyle medicine. Meaningful weight loss is achievable during active surveillance, and the parent PALS trial documented favorable changes in fasting insulin, C-peptide, and estimated insulin resistance, alongside favorable changes in adiposity at 12 months, though both groups lost lean mass without a significant between-group difference. But successful weight reduction does not guarantee that a patient will feel better over the next six months, and stability in quality-of-life scores cannot be credited to an intervention. As Campbell and colleagues have argued, lifestyle counseling remains reasonable despite uncertainty about its oncologic effects. What PALS adds is the corresponding qualification about patient-reported benefit: lifestyle care during active surveillance should begin with a goal set jointly by patient and clinician, and its value should be judged against that goal, not against a promise of feeling better that the current evidence cannot yet support.

Subject of Research: Health-related quality of life outcomes of dietary and exercise interventions in men with prostate cancer on active surveillance

Article Title: Defining benefit from lifestyle interventions during active surveillance

Article References: May, M., Brookman-May, S., Takemura, N., & Crevenna, R. (2026). Defining benefit from lifestyle interventions during active surveillance. Supportive Care in Cancer, 34(11), Article 1088. https://doi.org/10.1007/s00520-026-11299-1

Image Credits: AI Generated

DOI: 10.1007/s00520-026-11299-1

Keywords: prostate cancer, active surveillance, lifestyle intervention, quality of life, weight loss, exercise oncology, PALS trial, diet, clinical trials, supportive care, patient-reported outcomes, cancer survivorship