Dr. Dawn M. Mussallem: The importance of lifestyle medicine for cancer prevention and survivorship

Editor's note: Dr. Dawn M. Mussallem is no longer a provider at Mayo Clinic.

 

In this conversation, Dawn M. Mussallem, D.O., reflects on what decades of caring for people with and at risk for breast cancer have taught her about prevention, survivorship, and healing. Drawing on both clinical experience and personal insight, she explores the powerful—and often underestimated—role of lifestyle medicine, stress physiology, and whole‑person care in shaping cancer risk, treatment tolerance, and quality of life. Her perspective reframes prevention not as fear‑based restriction, but as an evidence‑grounded path toward vitality, resilience, and living fully, even in the face of uncertainty.

Why does lifestyle medicine matter so much to you?

Lifestyle medicine matters to me because I have witnessed it transform the arc of a life in ways that medicine alone cannot. Over decades of caring for people with breast cancer and those at elevated risk, I have seen fear, uncertainty, and a deep longing to feel safe in one’s body again.

Lifestyle is often where that sense of safety begins to return. It is where hope shifts from something fragile to something grounded. Not optimism, but the steady understanding that there are still meaningful ways to influence health, resilience, and how life is lived. It is where people move beyond simply surviving illness and begin to experience vitality, connection, and aliveness, sometimes for the first time in years.

This is not about blame. It is about power.

When we anchor prevention and survivorship in evidence-based nutrition, movement, sleep, stress regulation, and connection, we are not simply reducing risk. We are restoring vitality, improving treatment tolerance, supporting immune and metabolic health, and improving quality of life. That is why major oncology and public health organizations including the American Institute for Cancer Research (AICR), the National Comprehensive Cancer Network (NCCN), the American Society of Clinical Oncology (ASCO), and the American Cancer Society (ACS) recognize lifestyle interventions such as physical activity, nutrition, and stress management as essential components of cancer prevention and care.

These organizations now support exercise, dietary patterns, and behavioral interventions as evidence-based strategies associated with improvements in physical function, fatigue, mood, treatment tolerance, and overall quality of life across the cancer continuum.

Healthy lifestyle patterns extend life expectancy in the general population, and compelling evidence shows these same benefits among people living with and beyond cancer.

For me, this work is also deeply personal. I know what it feels like to sit on the other side of the exam room. My lived experience has made me deeply committed to helping people identify what is modifiable, what is possible, and what can still be reclaimed.

When we care for the whole person, body, mind, and spirit, we create the conditions for true healing and flourishing.

 

What are the most overlooked opportunities for prevention in breast cancer?

Three areas are consistently underestimated: metabolic health, alcohol, and the combined power of movement and whole food plant nourishment.

We have made prevention feel complicated, when many of the highest impact levers are surprisingly practical. Insulin resistance, visceral adiposity, chronic inflammation, and poor sleep are not abstract concepts. They are modifiable biological drivers that influence hormones, immune surveillance, and inflammatory signaling.

Women in the highest quartile of insulin resistance have a 34 to 78 percent higher risk of breast cancer compared with those in the lowest quartile. Importantly, metabolically unhealthy individuals with normal body weight carry elevated risk, while metabolically healthy individuals with higher body weight do not. This underscores that metabolic health may be more biologically relevant than adiposity alone.

Alcohol remains minimized in both public discourse and clinical conversations. Many people are unaware that even social drinking carries a measurable breast cancer risk over time. One drink per day increases breast cancer risk by approximately 5 to 15 percent, with no safe threshold. This is one of the few modifiable risk factors where small changes can lead to meaningful population level impact, yet it is often culturally normalized and overlooked. Both the American Cancer Society and AICR identify alcohol reduction as a key cancer prevention strategy.

Physical activity is profoundly underutilized in cancer prevention. The evidence is striking. Individuals with the highest levels of physical activity have a 10 to 25 percent lower risk of breast cancer compared with those who are least active, across both premenopausal and postmenopausal populations.

The DELCaP study demonstrated that meeting physical activity guidelines before and after diagnosis was associated with a 41 percent reduction in recurrence and a 49 percent reduction in mortality. Even brief bursts of vigorous activity embedded into daily life, such as fast walking or stair climbing, confer meaningful cancer prevention benefits. NCCN, ASCO, ACS, and AICR all recommend regular physical activity as a core component of cancer prevention and survivorship care.

Whole food plant nourishment is equally transformative. Current NCCN and AICR guidelines explicitly recommend a predominantly plant-based dietary pattern for breast cancer risk reduction, emphasizing vegetables, fruits, legumes, whole grains, and fiber-rich foods.

Adherence to a healthful plant-based dietary pattern is associated with an 11 to 23 percent reduction in breast cancer risk, with the strongest protective associations seen in estrogen receptor negative tumors. Women with the highest adherence to high quality plant foods experience a 21 percent lower overall breast cancer risk and a 26 percent lower risk of estrogen receptor negative disease.

Importantly, quality matters. Diets dominated by refined grains, ultra-processed foods, and added sugars increase breast cancer risk by approximately 20 percent.

I would also add loneliness and chronic stress physiology. These are harder to quantify, so they are easier to ignore. Yet they profoundly shape behavior, biology, sleep, metabolic health, and adherence to every other prevention strategy.

The evidence is now definitive. The DELCaP study showed that individuals with the strongest adherence to cancer prevention lifestyle recommendations experienced a 37 percent reduction in recurrence and a 58 percent reduction in all cause mortality. In primary prevention, adherence to AICR and World Cancer Research Fund guidelines has been associated with more than a 50 percent reduction in breast cancer occurrence when comparing highest to lowest adherence. A comprehensive 2025 meta analysis confirmed a 20 percent overall reduction in breast cancer risk with guideline adherence, rising to 24 percent in postmenopausal women.

These are not marginal gains. These are interventions that change the arc of a life. And we are still not talking about them enough.

What have your patients and your own journey taught you about the role of stress in healing?

My patients have taught me that stress is not just emotional. It is biological. Chronic stress alters sleep, appetite, inflammation, cognition, relationships, and the capacity to engage in care. When the body remains in sustained threat mode, it pays a physiologic price.

At the biological level, chronic stress activates beta adrenergic and glucocorticoid signaling pathways that influence inflammation, immune suppression, tumor progression, and treatment response. These mechanisms are now well described in the scientific literature.

My own journey taught me something equally important. Healing is not only about controlling disease. Healing is about reconnecting to life.

When we support stress regulation through breathwork, movement, time in nature, meaningful connection, spiritual practice, therapy, and creative expression, we are not offering optional extras. We are restoring the physiologic conditions that allow healing to occur.

The evidence is clear: mindfulness based stress reduction, cognitive behavioral therapy, and relaxation interventions significantly reduce anxiety and depression and improve quality of life in people with cancer, with moderate effect sizes. Digital stress management interventions demonstrate sustained benefits for perceived stress, mood, and self regulation over twelve months. ASCO and NCCN guidelines support mindfulness, cognitive behavioral therapy, yoga, and stress management as evidence-based interventions for cancer related fatigue, anxiety, and depression.

Importantly, mind body interventions also enhance meaning, purpose, post traumatic growth, and spirituality. These are outcomes that people consistently report as deeply important, even when they are more difficult to measure.

I have learned to be gentle with the word stress. Many people hear it and assume they are failing. I often reframe the conversation to a different question: how can we help your nervous system feel safe again?

That is when repair becomes possible. That is when people reconnect to love, purpose, and the experiences that make life meaningful.

I begin by naming the truth. People at high risk often carry invisible fear. So I lead with clarity, compassion, and care, and then I simplify.

I frame risk reduction as a portfolio, not a single perfect decision. The plan is personalized, stepwise, and aligned with a person’s values. The goal is not to create a life organized around fear. The goal is to build a life that feels strong, steady, and fully lived.

We always start with primary prevention, because this is where the greatest power lies. Adherence to American Institute for Cancer Research (AICR) lifestyle patterns has been associated with a 50 to 60 percent reduction in breast cancer risk. These patterns include daily movement, a whole food plant predominant diet, metabolic health optimization, restorative sleep, stress regulation, and limiting alcohol. These behaviors are also endorsed by NCCN, ACS, and ASCO as foundational to cancer prevention and survivorship.

These are not optional add ons. They are the biological foundation of prevention and long-term health.

Next, we discuss secondary prevention through early detection. I recommend annual mammography beginning at age 40 for average risk women. Lives are saved in the 40 to 49 age group, and for me, one life saved is enough.

Women with a family history of breast cancer, known genetic mutations, prior chest radiation, high risk breast lesions, or elevated calculated lifetime risk should begin earlier.

For women with a lifetime breast cancer risk of 20 percent or greater, annual mammography with tomosynthesis plus annual contrast enhanced breast MRI is recommended by NCCN and ACS. MRI detects cancers earlier, at smaller sizes, and with lower rates of lymph node involvement.

In women with BRCA mutations or moderate risk genes such as ATM, CHEK2, and PALB2, combined MRI and mammography reduce breast cancer mortality by more than 50 percent.

When increased breast density is the primary risk factor, supplemental imaging is encouraged. At Mayo Clinic, this is individualized. When MRI is not appropriate, other validated modalities such as molecular breast imaging may be used.

We then discuss chemoprevention for selected high risk women. These medications do not reduce mortality, but they meaningfully reduce the occurrence of breast cancer.

For premenopausal women, tamoxifen reduces breast cancer risk by nearly 50 percent overall and by more than 80 percent in women with atypical hyperplasia. Low dose tamoxifen offers comparable benefit with improved tolerability. For postmenopausal women, options include tamoxifen, raloxifene, or aromatase inhibitors, which reduce invasive breast cancer risk by approximately 44 to 65 percent depending on the agent.

The choice is individualized based on menopausal status, bone density, uterine status, clotting history, and personal preferences. We discuss trade offs openly and monitor carefully. The goal is informed choice, not perfection.

Finally, I protect joy. The plan must be livable. If it is not sustainable, it becomes another source of stress.

I often say we are not trying to make you perfect. We are trying to make you powerful. Then we take the next right step.

When we honor autonomy and meet people where they are, transformation becomes possible.

 

If you could inspire more researchers or clinicians to explore one overlooked aspect of cancer care, what would it be and why?

I would elevate the integration of stress physiology, connection, meaning, and purpose into standard cancer care. Not as abstract concepts, but as measurable and clinically actionable variables.

We are exceptional at imaging and pharmacology. Yet we still underinvest in the factors that shape adherence, immune function, metabolic health, inflammation, and quality of life. Chronic stress influences tumor biology through neuroendocrine activation, immune dysregulation, inflammation, and impaired immune surveillance.

The evidence for mind body and psychosocial interventions is now robust. These approaches improve anxiety, depression, fatigue, and quality of life, with effect sizes comparable to many pharmacologic interventions. Meaning centered therapies reduce depressive symptoms by enhancing purpose and connection.

I envision a future where nutrition, exercise, sleep, and nervous system regulation are treated with the same seriousness as medications, and where community and belonging are recognized as essential components of care.

Current NCCN and ASCO guidelines already support physical activity, mindfulness, yoga, cognitive behavioral therapy, and stress reduction as evidence-based interventions for cancer related fatigue, anxiety, and depression.

Lifestyle medicine interventions consistently improve metabolic markers, perceived stress, confidence in self management, and quality of life. People exceed activity guidelines, feel more capable, and reconnect with joy.

Because the goal is not just survival. The goal is aliveness. The goal is helping people reconnect to what makes life worth living.

When we care for the whole person, we do more than extend life. We restore it.

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