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 »  Abstract
 » Introduction
 » Studies on TENS
 »  Studies on Scram...
 »  Our Perspective ...
 » Conclusion
 »  References
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  Table of Contents  
Year : 2022  |  Volume : 59  |  Issue : 2  |  Page : 282-287

Looking beyond the obvious: Role of non-invasive electroanalgesia in management of cancer pain

Department of Physiotherapy, M S Ramaiah Medical College, Bengaluru, Karnataka, India

Date of Submission13-Dec-2020
Date of Decision11-Feb-2021
Date of Acceptance15-Mar-2021
Date of Web Publication29-Jun-2022

Correspondence Address:
Sundar Kumar Veluswamy
Department of Physiotherapy, M S Ramaiah Medical College, Bengaluru, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijc.IJC_1340_20

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 » Abstract 

Pain is considered as one of the most debilitating symptoms of cancer and its treatment. Owing to the limited efficacy of traditional pharmacological interventions to address cancer pain in its entirety, an avenue exists for exploration into nonpharmacological therapies. Analgesia using non-invasive electrotherapeutic modalities such as transcutaneous electrical nerve stimulation (TENS) and scrambler therapy emerges as a viable option to address cancer pain. The inability of these modalities to find a place within the recommended clinical guidelines has possibly resulted in the paucity of application of the same within the clinical setup. This perspective article aims at stimulating a discussion surrounding the inclusion of non-invasive neuromodulatory treatment techniques such as TENS and scrambler therapy to combat cancer pain and explore the benefits and pitfalls of using these techniques as an adjunct to the pre-existing treatment strategies. It is envisioned that this opinion piece will open a dialogue about a possible home for non-invasive electroanalgesia within the clinical treatment pathway for cancer pain.

Keywords: Biopsychosocial model, scrambler therapy, transcutaneous electrical nerve stimulation, World Health Organization analgesic ladder

How to cite this article:
Verma R, Shivadeva M, Bhupal DP, Veluswamy SK. Looking beyond the obvious: Role of non-invasive electroanalgesia in management of cancer pain. Indian J Cancer 2022;59:282-7

How to cite this URL:
Verma R, Shivadeva M, Bhupal DP, Veluswamy SK. Looking beyond the obvious: Role of non-invasive electroanalgesia in management of cancer pain. Indian J Cancer [serial online] 2022 [cited 2022 Oct 6];59:282-7. Available from:

 » Introduction Top

Cancer pain is multifactorial and complex; it may arise out of the disease pathology, its treatment, or secondary complications. Despite the emergence of the biopsychosocial model of care, current strategies for the management of cancer pain predominantly use a biomedical approach.[1] The World Health Organization (WHO) analgesic ladder suggests a sequential use of drugs, moving from non-opioids to strong opioids as a management strategy.[2] The European Society for Medical Oncology and the Spanish Society of Medical Oncology clinical guidelines also recommend pharmaceutical management for cancer pain.

Pharmacological regimens have their own challenges; patients may exhibit varying sensitivities to the adverse effects associated with the long-term analgesic treatment, and alleviation of pain may require more than one analgesic. The type and extent of cancer may also limit the route of administration of analgesics in some patients.[3] Various modifications, including a recent suggestion to reconfigure the WHO analgesic ladder to prioritize alternative invasive procedures over opioid administration, have also been observed.[4]

Despite several proposed revisions to the analgesic ladder, the use of non-invasive electrical neurocutaneous stimulation techniques such as transcutaneous electrical nerve stimulation (TENS) and scrambler therapy as an adjuvant therapy have not found their place in the regimen. TENS is based on the “gate control theory” of pain, where surface electrodes stimulate A-beta fibers that inhibit pain transmission, whereas scrambler therapy focuses on stimulating C fibers and transforming the information of pain into “nonpain” using the same pathways via artificial neurons.[5] In addition to being effective as pain control measures, TENS and scrambler therapy are also well tolerated with no serious adverse events and allow the user autonomy over their pain control. Anecdotal evidence from our clinical practice is suggestive of their effectiveness in the management of cancer pain. Through this perspective, we intend to provide an overview of the current literature with an aim to pique curiosity among the readers to consider the possible inclusion of non-invasive electroanalgesic options such as TENS and scrambler therapy as an adjuvant in treating cancer pain.

For this opinion piece, we chose to examine all articles identified by a combination of several databases, including PubMed/MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar. Search terms, including “Scrambler Therapy,” “Calmare Therapy,” “TENS,” and “Cancer Pain” were used and combined using Boolean terminology. We were interested in identifying articles that showed the effects (both positive and negative) of TENS and scrambler therapy on cancer pain. Such articles were reviewed and reported with the analytical intent that was primarily descriptive.

In the absence of any importance attributed to non-invasive electroanalgesic approaches to cancer pain management in current clinical practice guidelines, we started with the premise that there would be scant evidence of benefits for such methods. Contrary to our expectations, the literature search yielded a significant number of studies that alluded to their benefit in the management of cancer pain. As we used an exploratory approach to screen for evidence of benefits, we were more inclusive in selecting articles and did not go by the standard approach of grading the quality of evidence as is usually performed in a systematic review. In brief, we identified and summarized 22 studies: 11 studies each pertaining to TENS and scrambler therapy. The studies exploring TENS and scrambler therapy varied in study design ranging from case reports, single-group pre-post design to randomized controlled trials (RCTs).

 » Studies on TENS Top

The literature search identified a veritable mix of studies in an array of cancers. Details of the study characteristics and their findings are summarized in [Table 1]. Among the 11 studies identified, nine suggested improvements in varied parameters such as pain severity,[6],[7],[8],[9],[10],[11],[12],[13],[14] reduced oral analgesic dependence,[6],[7] chronic cancer pain,[9] fatigue[10] pain during movement and rest,[10],[14] and quality of life.[15] The two studies,[15],[16] although found beneficial on other parameters, failed to demonstrate pain relief. They did not lead to aggravation of symptoms either, and no adverse events were reported by any of the studies.
Table 1: Summary of Studies Using TENS for Management of Cancer Pain

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 » Studies on Scrambler Therapy Top

In the 11 studies identified through our search, all suggest positive benefits of scrambler therapy on cancer pain, the details of which are tabulated in [Table 2]. Moreover, the literature also suggests an improvement in chronic cancer pain not responding to pharmacological intervention,[17] chronic postmastectomy pain and postlumpectomy pain,[18] chemotherapy-induced neuropathic pain (CINP),[19] and ultimately the quality of life. The included studies employed outcome measures such as visual analog scale, numeric pain rating scale, and modified questionnaires that have been validated in measuring pain and changes in quality of life in the cancer population.[20] Scrambler therapy has varying degrees of efficacy with no substantial side effects. The limitations evidenced in the above literature arise from the lack of studies analyzing long-term effects of scrambler therapy.
Table 2: Summary of Studies Using Scrambler Therapy for Management of Cancer Pain

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 » Our Perspective on the Use of Noninvasive Electroanalgesia in Management of Cancer Pain Top

Maddening, unbearable, overwhelming, monstrous, and cruel are the descriptors patients with cancer ascribe to cancer pain.[13] Cancer pain is underrecognized, underreported, and undertreated. Women suffering from pain after breast cancer treatment avoid taking medication because of concerns about unwanted side effects.[29] Oral mucositis is cited as one of the most debilitating adverse effects of head and neck cancer treatment. Many patients suffering from oral mucositis have reported inadequate pain relief from topical medication.[30] Inadequate analgesia and inevitable side effects from traditional pharmacological intervention elucidate the need for nonpharmacological treatment modalities to act as an adjuvant to the pre-existing protocol.

Nonpharmacological management of pain, both acute and chronic, has been long advocated as a strategy with physiotherapy practice. This approach has been supported by moderate- to high-quality evidence in patients with chronic pain of various origins. Non-invasive electroanalgesia is one such approach within the ambit of nonpharmacological interventions for pain along with more invasive techniques such as percutaneous electrical nerve stimulation, electroacupuncture, and spinal cord stimulation.

In this review, we have summarized the literature on the effectiveness of two such non-invasive neuromodulatory techniques: TENS and scrambler therapy. Although both use therapeutic electrical stimulation, they differ in their mode of action. TENS causes changes in the somatotopic organization in the parietal cortex resulting in increased attention to painful processes, which causes an inhibition in the transmission of the painful stimuli,[24] whereas scrambler therapy replaces “pain” with “nonpain” signals resulting in an immediate reduction in pain with appropriate electrode placement.[26] Relief from cancer pain through the use of non-invasive neuromodulatory techniques is documented across various cancer types and chronicity. Patients with head and neck cancers experienced ā reduction in mucositis pain at rest[14] and bone pain during function,[11] through the application of TENS. Scrambler therapy has shown improvement in CINP[19],[22] and intense drug-resistant visceral pain.[17] Also, these electroanalgesia methods present the added benefit of not overwhelming the body systems already burdened by the cancer treatment as they do not need to be metabolized and for the most part are easy to use and cost-effective.[10]

WHO suggests quality of life as an important outcome measure in studies related to pain management.[31] Scrambler therapy and TENS have reported improvement in the quality of life of the patients. Through 10 weeks of follow-up in a study, the Global Impression of Change scale showed improvement in quality of life through the application of scrambler therapy;[26] another study suggested a reduction in pain interference with the use of TENS, extrapolating an improvement in the quality of life through their ability to perform activities of daily living without difficulty while using the machines.[9]

Reduction in the adverse effects of cancer treatment is not limited to just pain. In patients with CINP, numbness and tingling are reported to be more bothersome than pain; scrambler therapy has been shown to have a positive effect on that as well.[19],[24] An overall improvement in general activity, mood, sleep, and enjoyment of life is also noted.[24] A few studies noted the reduction in the analgesic intake[25] and a complete cessation in one case.[17] Physical, psychological, social, and environmental health was seen to show improvement post scrambler therapy.[17]

Crucial facets of chronic pain management are autonomy, validation, and a sense of control.[32] The benefit of talking to a health care professional about their pain cannot be overstated. Active participation of the patient in their treatment through the use of machines such as TENS encourages a self-management approach during a time when they need a sense of control the most.

These non-invasive electrotherapeutic approaches, much like the pharmacological approaches, are not without limitations. The analgesic benefits of TENS are the greatest during stimulation,[33] but there are discrepancies in the longevity of the pain relief post-treatment, which warrants further research. Continuous stimulation also runs the risk of analgesic tolerance or habituation.[10] For optimal analgesic effect, expertise in electrode placement is required during scrambler therapy; this is a necessity with TENS.

Limited clinical and academic interest in non-invasive neuromodulatory techniques, despite experts in the field elucidating the benefits of TENS in the management of cancer-related pain and studies indicating scrambler therapy's efficacy and safety in patients with pain not responsive to any treatments, particularly opioids,[5] is a missed opportunity.

Research in the field of non-invasive electroanalgesia is still in its infancy. Long-term, large multicenter RCTs with a homogeneous sample are required, which can provide an avenue for future work in the area. Analyzing the longevity of the effects and construction of a precise application protocol for TENS and scrambler therapy in the cancer population using well-designed clinical trials and large multicenter RCTs can be considered for future research and would benefit the field.

 » Conclusion Top

The existing literature provides us with a good starting point to consider non-invasive electroanalgesia as a means for controlling cancer pain, improving the functional abilities of these patients along with the adverse effects of cancer treatment, and ultimately improving their quality of life. Considering the benefit–risk relation, the inclusion of TENS and scrambler therapy in the treatment tool belt weighs heavily on the benefit side. A non-invasive, nonpharmacological approach is a promising complementary approach worth considering as a beneficial adjunct to the multimodal treatment of cancer pain.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

 » References Top

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World Health Organization. WHO guidelines for the pharmacological and radiotherapeutic management of cancer pain in adults and adolescents. World Health Organization, Geneva. 2018. Available from:  Back to cited text no. 2
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  [Table 1], [Table 2]


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