The role of opioids in cancer progression

Problems with opioids beyond misuse

The U.S. is grappling with an opioid epidemic, with millions of adults on long-term opioid therapy (LTOT). Although patients often report pain relief and improved daily function with opioids, research shows no significant differences in short-term outcomes between opioid and non-opioid users, as well as no long-term opioid benefits. This scoping review aims to identify lesser-known side effects of long-term opioid use and increase awareness of them, allowing healthcare providers and patients to better assess the risks and benefits of opioid use. Our data search from PubMed and Google Scholar used keywords related to opioids, chronic pain, hypogonadism, endocrinopathies, cancer progression, cardiovascular events, renovascular events, sleep disturbances, mood disorders and others, narrowing down to English-language full articles published from January 2018 to April 2023. This review emphasizes the probable serious adverse consequences of long-term opioid use on various body systems in patients with chronic pain. Given the lack of long-term benefits and significant adverse effects, our review underscores the critical need for healthcare providers to include these risks in discussions with patients when considering the long-term use of opioid therapy.

Opioids in cancer: The κ‑opioid receptor (Review)

The κ‑opioid receptor (KOR) is one of the primary receptors of opioids and serves a vital role in the regulation of pain, anesthesia, addiction and other pathological and physiological processes. KOR is associated with several types of cancer and may influence cancer progression. It has been proposed that KOR may represent a new tumor molecular marker and provide a novel basis for molecular targeted therapies for cancer. However, the association between KOR and cancer remains to be explored comprehensively. The present review introduces KOR and its association with different types of cancer. Improved understanding of KOR may facilitate development of novel antitumor therapies.

Perioperative pain, analgesics and cancer-related outcomes: where do we stand?

Cancer-related pain is one of the most common and debilitating symptoms among cancer patients. Undertreated cancer-related pain interferes with daily activities and increases morbidity and mortality. While opioids continue to play an essential role in treating moderate to severe cancer-related pain, they are associated with many adverse effects including misuse. While preclinical and retrospective studies have shown a negative association between opioid use and cancer outcomes, randomized control trials demonstrate that opioid use does not influence cancer recurrence. Additionally, analgesics and adjuvants used for perioperatively or chronic pain control are unlikely to improve oncological outcomes. This article focuses on the pharmacological management of cancer-related pain and offers an overview regarding the use of these medications perioperatively and the cancer outcomes.

A randomized single-blinded, parallel-arm group feasibility trial evaluating role of pectoral nerve block on serum vascular endothelial growth factor levels in patients undergoing unilateral modified radical mastectomy

Metastatic breast cancer cells carry adult and neonatal variants of NaV1.5 voltage-gated activated Na⁺ channels involved in cell invasion. We hypothesize that instilling lignocaine near the surgical field to anesthetize the pectoral nerves for analgesia will decrease angiogenesis by blocking voltage-gated activated Na⁺ channels. Twenty patients undergoing unilateral modified radical mastectomy were randomized in a single-blinded, parallel-arm group feasibility pilot study in two groups. In Group I a catheter was placed between the pectoralis major and minor muscle under direct vision before skin closure. Ten milliliters of 2% lignocaine was given as an initial bolus followed by 10 mL of 2% lignocaine every 8 hours up to 24 hours. Group II did not receive any regional block. Primary measure outcomes were pre and postoperative changes in levels of vascular endothelial growth factor. Secondary outcomes were postoperative pain scores and total rescue analgesia used. Nine patients in each group were analyzed. Baseline demographic data of all females were similar with respect to age, body mass, height and duration of anesthesia. Postoperative mean serum levels of vascular endothelial growth factor were decreased by 46.60% from baseline in Group I, while were increased by 84.27% as compared to preoperative values in Group II. Postoperative average pain scores were less in Group I. Postoperative rescue analgesia in 24 hours in Group I was lower than that in Group II. There was no postoperative adverse event related to catheter or lignocaine administration at given doses. Instilling lignocaine to block pectoral nerves provides better postoperative analgesia and decreases a marker of angiogenesis. The study protocol was approved by the Institutional Ethical Committee of the Tertiary Centre (All India Institute of Medical Sciences Rishikesh India) (No. AIIMS/IEC/19/1002) on August 9, 2019, and the larger expansion trial was prospectively registered on Clinical Trial Registry India (No. CTRI/2020/01/022784) on January 15, 2020.