Over- and undertreatment in older adults took center stage at the SIOG 2025 Annual Conference in Ghent, where a packed plenary in the Jan & Hubert Van Eyck auditorium examined one of geriatric oncology’s most challenging questions: when are clinicians giving too much treatment, when too little—and who ultimately decides?
Titled “Defining and preventing overtreatment and undertreatment in older adults with cancer” plenary session was chaired by William Dale (Duarte, United States) and Clark DuMontier (Boston, United States). Bringing together oncologists, geriatricians, ethicists and a patient partner, the session argued that the field is ready to move from vague labels toward standard, ethically grounded criteria – and to anchor decisions in geriatric assessment and what matters most to patients.
Why “over” and “under” treatment need a universal language
William Dale opened the session by noting that “overtreatment” and “undertreatment” are used constantly in geriatric oncology but rarely defined. His scoping review of 200+ articles showed undertreatment was usually described as giving “less than standard” therapy, while overtreatment referred to intensive care where harms outweigh benefits—definitions that focused heavily on survival and overlooked geriatric factors and patient goals.
To bring clarity, Dale and Clark DuMontier proposed practical definitions: overtreatment is giving more intensive therapy when a less intensive option would offer equal or greater benefit with less harm; undertreatment is giving too little therapy—or proceeding without a geriatric assessment—when a patient would benefit from more.
A Delphi study confirmed these definitions align with core ethical principles, reinforcing Dale’s point that geriatric assessment and understanding patient preferences are ethical essentials in caring for older adults.
Geriatric assessment as the anchor to avoid both extremes
Picking up the “napkin diagram,” Melissa Loh (Rochester, United States) focused on the role of geriatric assessment in making the abstract framework clinically actionable.
Using the plenary’s anchor case – a 70-year-old with localized pancreatic adenocarcinoma being considered for Whipple surgery and perioperative chemotherapy – she contrasted two scenarios: one patient with essentially no impairments on geriatric assessment and another with multiple deficits in daily functioning, physical performance, cognition, polypharmacy and weight loss.
In the first scenario, for a fit older adult with potentially curable disease, not offering standard surgery and combination chemotherapy drifts into undertreatment, because the potential net benefit clearly exceeds the expected harm. In the second, proceeding with the same intensive approach without addressing vulnerabilities risks overtreatment, with harms likely to dominate.
Loh showed how geriatric assessment operates on several levels. First, it establishes baseline vulnerability, allowing clinicians to position the patient along the fit–frail axis of the diagram. Second, it opens opportunities for optimization and prehabilitation – for example, improving nutrition, strength, mobility or social support – which can shift the balance toward greater net benefit and expand the range of safely deliverable treatment. And third, it makes visible which vulnerabilities are modifiable and which are not, helping teams avoid unrealistic expectations about how far a frail patient can be “moved” toward fitness.
Crucially, she emphasized that fitness is context-specific. Being fit enough for immunotherapy is not the same as being fit enough for a Whipple procedure or triplet chemotherapy. The same geriatric assessment data must be interpreted differently depending on the proposed treatment, reinforcing the need for structured geriatric input rather than informal “eyeball” assessments.
Asking what matters: preferences as the missing dimension
Suzanne Festen (Groningen, Netherlands) emphasized that preventing over- and undertreatment requires more than clinical and geriatric data—it also requires understanding patient values and goals. Using an integrated decision model, she described three essential inputs for every major treatment decision: guideline-based options, the patient’s health and functioning, and the patient’s preferences.
To explore “what matters,” her team uses the Outcome Prioritization Tool, which helps patients weigh outcomes such as life extension, independence, and symptom relief. These priorities shift how patients perceive benefit and harm; for example, a fit patient who values independence may see a major operation as more burdensome than one who prioritizes survival.
Festen noted that clinicians often misjudge what older adults value, and many never explicitly ask. She urged the audience in Ghent to move from “we talk, they listen” to meaningful conversations that begin with questions like, “What will this treatment do for you?” Only by combining treatment options, vulnerabilities, and preferences can clinicians truly determine whether care is appropriate—or too much or too little.
“Don’t just treat the cancer – treat the person”
The final word came from Ann Pennella (Caledonia, United States), who shared her experience of stage I anal cancer at age 65. Unsure whether concurrent chemoradiation was overtreatment, she raised her concerns—prompting her oncologist to review the evidence with her, discuss uncertainties, and align the plan with her goals. That transparent exchange, she said, turned a frightening decision into one she could trust.
Pennella described ethical care as combining geriatric assessment, oncologic expertise, and what matters most to the patient. She urged clinicians in Ghent to close the gap between evidence and practice so that every older adult receives care calibrated to their vulnerabilities and values.
Her message echoed the plenary’s core theme: overtreatment and undertreatment are not about “how much” treatment is given, but whether it is right for the individual older patient.
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