Towards precision pain medicine for pain after cancer: the Cancer Pain Phenotyping Network multidisciplinary international guidelines for pain phenotyping using nociplastic pain criteria.

Pain after cancer remains underestimated and undertreated. Precision medicine is a recent concept that refers to the ability to classify patients into subgroups that differ in their susceptibility to, biology, or prognosis of a particular disease, or in their response to a specific treatment, and thus to tailor treatment to the individual patient characteristics. Applying this to pain after cancer, the ability to classify post-cancer pain into the three major pain phenotypes (i.e. nociceptive, neuropathic, and nociplastic pain) and tailor pain treatment accordingly, is an emerging issue. This is especially relevant because available evidence suggests that nociplastic pain is present in an important subgroup of those patients experiencing post-cancer pain. The 2021 International Association for the Study of Pain (IASP) clinical criteria and grading system for nociplastic pain account for the need to identify and correctly classify patients according to the pain phenotype early in their treatment. These criteria are an important step towards precision pain medicine with great potential for the field of clinical oncology. Within this framework, the Cancer Pain Phenotyping (CANPPHE) Network, an international and interdisciplinary group of oncology clinicians and researchers from seven countries, applied the 2021 IASP clinical criteria for nociplastic pain to the growing population of those experiencing post-cancer pain. A manual is provided to allow clinicians to differentiate between predominant nociceptive, neuropathic, or nociplastic pain after cancer. A seven-step diagnostic approach is presented and illustrated using cases to enhance understanding and encourage effective implementation of this approach in clinical practice.

Nutrition/Dietary Supplements and Chronic Pain in Patients with Cancer and Survivors of Cancer: A Systematic Review and Research Agenda.

BACKGROUND: Chronic pain is one of the most often seen, but often undertreated, sequelae in survivors of cancer. Also, this population often shows significant nutritional deficiencies, which can affect quality of life, general health status, and even risk of relapse. Given the influence of nutrition on brain plasticity and function, which in turn is associated with chronic pain in the population with cancer, it becomes relevant to focus on the association between pain and nutritional aspects in this population. OBJECTIVE: To identify relevant evidence regarding nutrition and chronic pain in patients with cancer/survivors of cancer. STUDY DESIGN: Systematic review. METHODS: PubMed, Embase, and Web of Science were systematically searched for interventional and experimental studies that included patients with cancer /survivors of cancer with chronic pain, a nutrition-related observation/examination, and a pain-related outcome. Studies that complied with the inclusion and exclusion criteria were screened for methodological quality and risk of bias by using the Qualsyst (standard quality assessment criteria for evaluating primary research) tool. RESULTS: The 2 included studies entailed uncontrolled trials which examined different nutritional supplements usage in various patients with cancer (breast, gastrointestinal and gynecological  cancers). One study evaluated the effects of vitamin C, but did not report a change in pain outcomes. The other study, looking at the nutritional supplements glucosamine and chondroitin, found an improvement in pain after 12- and 24 weeks. LIMITATIONS: The limitations to the generalization of these results include the insufficient amount of eligible studies and diversity in therapeutic interventions and participant groups. CONCLUSION: The association between nutrition and chronic pain in patients with cancer /survivors of cancer is not well documented. The available studies are uncontrolled, and are therefore limited to draw firm conclusions. Additional research is highly needed, and a research agenda is proposed within this paper.

Lifestyle and Pain following Cancer: State-of-the-Art and Future Directions.

This review discusses chronic pain, multiple modifiable lifestyle factors, such as stress, insomnia, diet, obesity, smoking, alcohol consumption and physical activity, and the relationship between these lifestyle factors and pain after cancer. Chronic pain is known to be a common consequence of cancer treatments, which considerably impacts cancer survivors' quality of life when it remains untreated. Improvements in lifestyle behaviour are known to reduce mortality, comorbid conditions (i.e., cardiovascular diseases, other cancer, and recurrence) and cancer-related side-effects (i.e., fatigue and psychological issues). An inadequate stress response plays an important role in dysregulating the body's autonomic, endocrine, and immune responses, creating a problematic back loop with pain. Next, given the high vulnerability of cancer survivors to insomnia, addressing and treating those sleep problems should be another target in pain management due to its capacity to increase hyperalgesia. Furthermore, adherence to a healthy diet holds great anti-inflammatory potential for relieving pain after cancer. Additionally, a healthy diet might go hand in hand with weight reduction in the case of obesity. Consuming alcohol and smoking have an acute analgesic effect in the short-term, with evidence lacking in the long-term. However, this acute effect is outweighed by other harms on cancer survivors' general health. Last, informing patients about the benefits of an active lifestyle and reducing a sedentary lifestyle after cancer treatment must be emphasised when considering the proven benefits of physical activity in this population. A multimodal approach addressing all relevant lifestyle factors together seems appropriate for managing comorbid conditions, side-effects, and chronic pain after cancer. Further research is needed to evaluate whether modifiable lifestyle factors have a beneficial influence on chronic pain among cancer survivors.

Do Nutritional Factors Interact with Chronic Musculoskeletal Pain? A Systematic Review.

Dietary patterns may play an important role in musculoskeletal well-being. However, the link between dietary patterns, the components of patients' diet, and chronic musculoskeletal pain remains unclear. Therefore, the purpose of this review was to systematically review the literature on the link between dietary patterns, the components of patients' diet and chronic musculoskeletal pain. This review was conducted following the "Preferred Reporting Items for Systematic reviews and Meta-Analyses" (PRISMA) guidelines and was registered in PROSPERO with the registration number CRD42018110782. PubMed, Web of Science, and Embase online databases were searched. After screening titles and abstracts of 20,316 articles and full texts of 347 articles, 12 eligible articles were included in this review, consisting of nine experimental and three observational studies. Seven out of nine experimental studies reported a pain-relieving effect of dietary changes. Additionally, protein, fat, and sugar intake were found to be associated with pain intensity and pain threshold. In conclusion, plant-based diets might have pain relieving effects on chronic musculoskeletal pain. Patients with chronic rheumatoid arthritis pain can show inadequate intake of calcium, folate, zinc, magnesium, and vitamin B6, whilst patients with fibromyalgia can show a lower intake of carbohydrates, proteins, lipids, vitamin A-E-K, folate, selenium, and zinc. Chronic pain severity also shows a positive relation with fat and sugar intake in osteoarthritis, and pain threshold shows a positive association with protein intake in fibromyalgia.