Lung cancer is the third most common cancer in the country and is the leading cause of cancer-related death worldwide. Over the past 20 years, lung cancer rates in the U.S. — as well as the death rate — have been declining and the five-year survival expectancy is trending up. However, data collected from 2012 to 2018 shows lung cancer has a much lower survival rate for people in the U.S. (22.9%) compared to five-year survival estimates for other types of cancers, such as “female breast cancer” (90.6%) or cancer of the prostate (96.8%). That being said, survival rates vary based on stage of diagnosis with better rates for those with early diagnosis and localized disease (cancer has not spread) and much lower rates for advanced disease.
There are two main types of lung cancer: non-small cell lung cancer, or NSCLC, and small cell lung cancer, or SCLC. NSCLC includes large cell and squamous cell carcinomas and adenocarcinoma and accounts for 80% to 85% of lung cancers. Accounting for 10% to 15% of all lung cancers, SCLC also is called “oat cell cancer” and tends to grow and spread faster than NSCLC. Other subtypes of NSCLC, such as adenosquamous and sarcomatoid carcinomas, are much less common.
Lung Cancer Risk Factors
While a reduction in tobacco smoking is one reason for positive changes in lung cancer rates, there are many other risk factors including exposure to secondhand smoke; use of beta-carotene supplements by heavy smokers; family history of lung cancer; HIV/AIDS infection; and environmental risk factors such as radiation therapy, imaging tests including CT scans and radon exposure.
Although supplementing with beta carotene is a risk factor for people who smoke, there is evidence that eating more foods containing carotenoids can help decrease lung cancer risk. Studies have shown an inverse relationship between the consumption of a combination of fruit and vegetables and a lower risk of lung cancer. The same protective relationship has been associated with higher fruit intake, but studies evaluating vegetable consumption have yielded inconsistent results. Other research shows that a traditional Mediterranean dietary pattern may lower risk of developing lung cancer and that foods containing isoflavones may decrease risk in people who have never smoked. Limited research suggests those who are physically active may have a decreased risk of lung cancer.
Role of RDNs
Since both diet and physical activity may play a role in decreasing the risk of lung cancer, registered dietitian nutritionists can guide patients and clients regarding interventions and advice related to food, nutrition, dietary supplements and lifestyle factors. RDNs are critical members of the interdisciplinary cancer health care team and should assess patients with lung cancer diagnoses for malnutrition. Evidence has shown positive outcomes when RDNs provide medical nutrition therapy to adult cancer patients who are undergoing chemotherapy or radiation treatment. Nutritional interventions — especially during treatment — are key, and RDNs play a crucial role in helping to manage any potential side effects.
According to Dolores D. Guest, PhD, RD, a research assistant professor in the department of internal medicine’s division of epidemiology, biostatistics and preventive medicine at the University of New Mexico School of Medicine and director of the Behavioral Measurement and Population Science Shared Resource at the UNM Comprehensive Cancer Center, the location or type of lung cancer could cause several abnormalities and syndromes such as hypercalcemia, anemia, Cushing’s syndrome and others that need nutritional intervention. “It’s not uncommon for one thing to be resolved and another to appear,” Guest says. “Working with an RDN throughout treatment is very important for these patients.”
Oncology dietitian Tricia Cox, MS, RD, CNSC, LD, who works at Baylor Scott & White Medical Center in Dallas, Texas, explains that in her oncology research, many RDNs may have to focus their time on patients with head and neck cancer or esophageal tumors. The research Cox has helped to conduct shows RDNs are often understaffed in outpatient oncology settings and many of them must focus on the most critically ill patients. “While this is good for [critically ill] patients, RDNs are often unable to adequately see all of the patients who need to be seen,” she says. “This could include patients with lung cancer.”
While other members of the medical team serve critical roles, an RDN is qualified to understand the science of lung cancer and how treatment interplays with nutritional status. “RDNs are trained to be able to mitigate these effects in a very personal way, providing individualized advice so patients can make both incremental and overall improvements,” Guest says. Her research shows that the key role RDNs serve in treating high nutrition-risk cancer patients, such as those with lung cancer, is more appreciated by fellow oncology team members than ever before. “Oncologists and nurses really value and have come to rely on RDNs to be the experts when it comes to assessing and working with patients to meet their nutritional needs.”
Assessing Nutrition and Nutrient Needs
About 45% to 69% of people with lung cancer experience malnutrition, which is associated with reduced quality of life, increased symptom severity and shorter survival rates. Concurrent chemotherapy and radiation, radiation to the esophageal region and being classified with stage 3 or 4 cancer all increase the risk of malnutrition. Evidence supports using the Malnutrition Screening Tool to assess for malnutrition(undernutrition) in adults; the Academy and the American Society for Parenteral and Enteral Nutrition have released a joint consensus statement that serves as a guide for assessing malnutrition (undernutrition) in adults who may be at risk.
Guest emphasizes that malnutrition screening is crucial for people with lung cancer and should be conducted at diagnosis and at regular intervals using validated instruments without modifications. The Malnutrition Screening Tool and the Patient-Generated Subjective Global Assessment are both recognized by the Academy’s Evidence Analysis Library as being valid and reliable tools for “identifying malnutrition risk in adult oncology patients” and within inpatient and outpatient settings. “Nutrition issues that are addressed proactively — not reactively — set the patient up for the best possible outcome,” Guest says.
Nutrition therapy for people who have undergone treatment, such as radio or chemotherapies, is critical. Published in 2021, a systematic review of 25 studies suggests that taste function can be impaired as early as three weeks into radiotherapy treatment and can remain impaired for three to 24 months after treatment. For people undergoing chemotherapy, impaired taste function varied and was less predictable, according to the authors, and could occur within days of treatment. A few studies also included patient reports of experiencing reduced appetite and dietary intake.
In general, nutrient needs per day for those with lung cancer can range from 25 to 30 calories per kilogram of body weight and 1 to 1.5 grams of protein per kilogram of body weight. RDNs should complete ongoing nutrition assessments for patients or clients with lung cancer throughout treatment and adjust calorie and protein recommendations as needed. Pay close attention to symptoms that may impact nutrition, such as early satiety, nausea and vomiting, diarrhea or constipation, and oral problems such as altered taste, pain, dysphagia, dry mouth, problems chewing or mouth sores, as these can reduce the patient’s ability to meet nutrition needs.
Because people with lung cancer are at an increased risk of malnutrition, RDNs can help patients and clients maintain body weight and protect lean body mass.
“Lung cancer is often diagnosed at a later stage,” Guest says. Weight loss is very common for these patients, and it can occur or be exacerbated by factors such as the location of the tumor, metastasis or treatments including surgery, radiation and chemotherapy and immunotherapy medications. “RDNs work with these patients and their caretakers or families to mitigate the effect of malnutrition on their bodies, which can help them withstand long-term treatment and improve medical outcomes and quality of life.”
Preventing severe loss of muscle mass, or sarcopenia, is a top priority. Studies have shown 47% to 61% of patients already have sarcopenia before they start chemotherapy or chemoradiation therapy, respectively, for lung cancer. Additionally, sarcopenia increases adverse outcomes and mortality rates in those with cancer and is a hallmark of cancer cachexia, which is a multifactorial syndrome often associated with reduced food intake, systemic inflammation, and catabolic metabolism characterized by weight loss greater than 5% in the past six months (not related to simple starvation) or a body mass index under 20 with any degree of weight loss more than 2%, or muscle wasting consistent with sarcopenia (as indicated by the appendicular skeletal muscle index) and any degree of weight loss more than 2%. Nutrition for any patient with cancer cachexia increases up to 35 calories per kilogram of body weight per day and up to 2.5 grams of protein per kilogram of body weight per day.
Research shows nutritional counseling can help increase food intake in people with cancer-related weight loss. Some data also shows patients who followed nutrition counseling advice while being treated for head and neck cancer experienced better health outcomes such as increased muscle mass and survival rates. Unfortunately, some studies have shown that only 50% to 61% of patients who receive nutritional counseling are able or willing to follow an RDN’s advice due to a multitude of barriers. A recent study that included “dietitian-identified barriers” for patients with advanced forms of cancer and cachexia revealed that non-symptom related barriers — such as restrictions from a prior medical diagnosis, conflicting nutrition information or lack of motivation — were cited as barriers more often than those associated with symptoms.
In one study of 310 patients with lung cancer, those with better nutritional status had better emotional and social functioning as well as less severe symptoms including fatigue, nausea, vomiting, pain, dyspnea, loss of appetite, coughing, mouth or tongue pain, difficulty swallowing and hair loss. The most significant differences between the patients with normal nutritional status compared to the patients at risk of malnutrition or considered to be malnourished (based on the Mini Nutritional Assessment questionnaire) were improvements in insomnia, diarrhea, shortness of breath, tingling in the hands or feet, and chest, arm or shoulder pain.
For people identified as at risk of or diagnosed with malnutrition, RDNs can provide education on dietary strategies such as encouraging meals and snacks dense in calories and protein and ways to meet vitamin and mineral needs. Small, frequent meals and snacks can be helpful if appetite or intake is poor. Because many patients undergoing treatment for lung cancer may have trouble swallowing or have pain in the esophagus, texture modification may be needed.
Depending on the type of treatment, tube feeding or, in some cases, parenteral nutrition may be needed. Parenteral nutrition can be used if the gastrointestinal tract is not functioning or is not accessible, such as with a blockage in the digestive tract. Artificial nutrition in the form of enteral nutrition may be warranted if a patient isn’t able to meet their needs through diet alone. Enteral nutrition should be strongly considered if the patient is unable to eat food for a week or longer or if they only meet 60% or less of their needs through food for more than two weeks. It also should be considered if the patient is malnourished and has poor oral intake. For patients with other types of cancer (such as gastrointestinal), evidence shows nutrition interventions including modified oral diets and parenteral and enteral nutrition have the potential to not only improve outcomes, but also generate millions of dollars in cost savings annually.
Especially for those at risk for malnutrition and not meeting nutrient needs through food, it is wise to educate patients on appropriate and safe use of dietary supplements when warranted.
Omega-3 Fatty Acids
Omega-3 fatty acid supplementation may be helpful in maintaining weight and muscle mass, especially for those with advanced NSCLC undergoing chemotherapy. Potential benefits of omega-3 fatty acid supplements for those with lung cancer may include reduced inflammation and less severity of chemotherapy-induced oral and esophageal mucositis. However, more research is needed. Additional benefits include a potential reduction of peripheral neuropathy from chemotherapy drugs or increased effects/clinical benefits of other medications used in cancer treatment.
Possible Risks of Antioxidant Supplements
Research has shown that taking beta-carotene supplements increases the risk of lung cancer in people who smoke, especially one or more packs per day. Risk is further compounded in people who smoke and drink one or more alcoholic beverages per day.
Results from animal studies show that supplementing with N-acetylcysteine, or NAC, accelerates tumor progression, but more research is needed to support these findings in humans. Other studies indicate that both NAC and antioxidant vitamin E may promote cancer metastasis because they reduce the natural reactive oxygen species that cancer cells produce, which opens a path to tumor progression. This has been shown in both human and mouse lung cancer cell study models
Also, antioxidants may reduce enzyme activity designed to promote apoptosis (the process of programmed cell death). Conversely, some research on NAC based on in vitro studies with bromelain and gastrointestinal cancer cells indicates NAC may be used to enhance the cytotoxic effects of chemotherapy drugs while protecting host tissues from the drugs’ toxicity. However, supplements that contain NAC are technically illegal at this time due to being excluded from the Federal Food, Drug, and Cosmetic Act’s definition of a dietary supplement. NAC is available as a prescription drug, and the U.S. Food and Drug Administration is evaluating whether certain NAC-containing products can be lawfully marketed as dietary supplements in the future. The Natural Medicines database by TRC Healthcare also indicates NAC is currently “considered an unlawful ingredient in dietary supplements” and is “likely ineffective” for lung cancer.
The Vital Role of RDNs on the Cancer Care Team
RDNs working with lung cancer patients can provide nutritional counseling, supplement guidance and lifestyle modification suggestions to help improve outcomes. New research and analysis published in two articles in the February 2021 Journal of the Academy of Nutrition and Dietetics highlight the role nutrition may play in cancer risk and treatment, as well as the barriers cancer survivors face in maintaining a healthful diet.
According to one of the articles, American adult lung cancer survivors with obesity (ages 30 to 64 and current smokers) had a diet quality score that was significantly lower compared to the reference group, based on data from the National Health and Nutrition Examination Surveys from 2005 through 2016. In the study, adherence to the 2015-2020 Dietary Guidelines for Americans — specifically the dietary recommendations for whole grains, greens and beans, sodium and fatty acid — had “less than 50% of the maximum possible scores” based on the Healthy Eating Index 2015, which is a measure of diet quality. RDNs play an important role in providing nutrition education so cancer survivors can better meet these guidelines.
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