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Oncology-Specific Opioid Risk Calculator in Cancer Survivors
Despite the great progress made in terms of diagnosis and treatment, cancer is still a dreaded diagnosis. This devastating disease has a sweeping reach. The International Agency for Research on Cancer (IARC) figures for global cancer burden estimates were 19.3 million new cases and 10 million deaths in 2020. Access to pain relief is a major concern for cancer patients at all stages of the disease. Multiple cancer pain management studies indicate that survivors sometimes experience pain for months or years after cancer treatment. According to the study conducted by the American Society of Clinical Oncology (ASCO), about 40% of cancer survivors in the United States continue to experience chronic pain.
Opioids and cancer pain
Although opioid analgesia for noncancer-related pain might be controversial, oncologists and pain specialists rely heavily on opioids to treat pain from cancer, or pain because of treatment. In these applications, opioids are considered relatively safe, they exist in multiple routes of administration, and are ease of titration. Effectiveness in treating various types of pain – somatic, visceral, or neuropathic – is another reason why opioids are popular in pain management.
Besides being a potent analgesic, opioids are also common drugs of abuse because of their wide availability and euphoriant nature. Long-term usage of opioids can lead to dependence or unintentional overdosing. Furthermore, the potential toxicity of opioids can cause depression, confusion, respiratory depression, or even hyperalgesia. Hence, not all opioids are used in cancer pain management. For example, meperidine, propoxyphene, and nalbuphine.
Prevalence of opioid use and overdose
A literature review indicates that the prevalence of opioid addiction varies from 0% up to 50% and 0% to 7.7% in chronic non-cancer pain patients and cancer patients respectively. This may be an underestimation of the actual incidence considering the lack of efficient risk assessment tools.
A report of the International Narcotics Control Board on the Availability of Internationally Controlled Drugs showed a steep increase in prescribing opioids in Africa and South Asia, between 2001 and 2013. The same report also showed high cancer rated but moderate consumption of narcotics in Asia. Over the past ten years, North Americans and Europeans consumed about 90% of the world’s supply of morphine, suggesting an imbalance in the global pain and palliative care efforts.
A 2020 population-based study of 169162 respondents to the National Survey on Drug Use and Health reported higher prescription opioid use among cancer survivors than the ones without a cancer history. However, they couldn’t find conclusive evidence for prescription opioid misuse among the survivors.
Global trends in opioid analgesia may be complicated by regulatory changes in some regions. A clinical review conducted at MD Anderson Cancer Center in Texas revealed a significant reduction – from 78 to 40mg/day – in morphine equivalent daily dose (MEDD).
While there are debates over the opioid crisis and misuse, it should be noted that opioid-associated deaths are ten times less likely to occur in cancer survivors than the normal population.
Risk stratification & opioid risk score
Adopting the clinical practice guideline of the American Society of Clinical Oncology (ASCO), the need for risk stratification has been recognized and several tools have been developed for optimal cancer pain management. The Opioid Risk Tool (ORT) is a validated self-report screening tool that helps identify cancer patients at high risk for aberrant use of opioids. Potential predictors include younger age, genetic variables, drug convictions, family history of anxiety or depression, and more reported pain during treatment.
A risk score of 0-3 indicates a low risk, while 4 – 7 moderate risk, and 8 or above suggests the highest risk of opioid misuse after cancer treatment.
Being a high-risk patient doesn’t deter the oncologists from prescribing opioids, but should lead to strict monitoring, including perhaps the use of treatment consent forms/agreement, frequent appointments, or urine toxicology screening using chromatography or mass spectroscopy. Multi-modal approaches and tailored therapies, including psychological care, are recommended for high-risk patients.
Because of the high incidence of anxiety and depression, patients with poor compliance to opioids are more challenging to treat despite their disease stage. In advanced stages, 13-79% of the patients develop anxiety and depression is common in 3-77% of cancer patients.
Other opioid risk screening tools for assessing the risk of opioid misuse before commencing long-term opioid therapy include:
- Screener and Opioid Assessment for Patients with Pain Revised (SOAPP-R)
- Screening Instrument for Substance Abuse Potential (SISAP)
- Diagnosis, Intractability, Risk, and Efficacy score (DIRE)
- Current Opioid Misuse Measure (COMM)
- Patient Medication Questionnaire (PMQ)
Oncology-specific opioid risk calculator in cancer survivors
A clinical study by Paul Riviere et al aimed at the finding that cancer opioid risk score can be used to identify cancer survivors with a high likelihood of persistent future opioid use. In their cohort of 44,932 Medicare-aged cancer survivors, about 5.2% were persistent opioid users. The patients who became persistent opioid users had at least one comorbidity, including depression. Among the chronic prior opioid users, about 98.1% had a 21-day opioid supply in the first 4 months before commencing the therapy.
The researchers used a 5-factor predictive model to calculate cancer opioid risk score. Their calibration analysis concluded two-thirds of patients to be in the low-risk group and one-third of the patients in the moderate-risk group. And, a small fraction of patients fell in the high-risk category.
Clinical significance of opioid risk calculator in cancer pain management
Early detection of high-risk patients helps to prevent aberrant opioid behavior. In post-surgical rehabilitation, opioid abuse increases the risk of poor surgical outcomes, affects mental health, and even increases the risk of death, among a variety of other health issues. Although there is insufficient evidence to determine the effectiveness of opioid risk calculators, some prescription guidelines suggest the use of these tools. In this context, ORT can be used to risk-stratify cancer patients and to accurately predict opioid abuse.
Patients with high-risk profiles can benefit from risk-mitigation interventions. For example, increased caution is beneficial in terms of opioid selection, dosage, and better monitoring for opioid‐induced respiratory depression (OSORD). Knowing the risk score also lets clinicians educate family members or caregivers on naloxone rescue kits in the event of an opioid overdose.
Oncology-specific opioid risk calculators may be more useful in high-volume medical practices due to their relative ease of use.
The debate remains regarding the accuracy of opioid risk calculator tools to predict the risk of, or aid in the identification of, prescription opioid misuse. Despite the unclear validity across different populations, oncologists are strongly encouraged to use of risk assessment tools before initiating opioid treatment.
A thorough screening for personal or family history of psychiatric diseases, drug abuse, or preadolescent sexual abuse is key to identifying patients who need closer assessment.