Radiotherapy-induced Nausea and Vomiting

Kristopher Dennis; Ernesto Maranzano; Carlo De Angelis; Lori Holden; Shun Wong; Edward Chow

Disclosures

Expert Rev Pharmacoeconomics Outcomes Res. 2011;11(6):685-692. 

In This Article

Clinical Themes

Proof of Prevalence

It is well known informally that many radiation oncologists dispute RINV as being legitimate concerns for their patients. There are many explanations for this view. Treatments with prominent emetogenic potential such as total body, total nodal, half body and whole abdominal irradiation are now uncommon, and only a minority of radiation oncologists routinely prescribe upper abdominal radiotherapy. Many radiation oncologists then, by virtue of their anatomic subspecializations, may simply not observe much RINV and are thus not concerned by it. However, in this context 'not observing' RINV is fundamentally different from not detecting it, and if patients are not overtly nauseated or vomiting, lesser degrees of RINV can be missed. Review clinic appointments for patients undergoing radiotherapy typically occur only once weekly, and history taking and physical examinations are very focused. Depending on the site being treated, rectal or bladder irritation, mucositis, skin toxicity or pain may be the most pressing concerns for radiation oncologists during these brief appointments, and probing about RINV or other more 'general' concerns is not a priority, especially during presumed nonemetogenic radiotherapy. However, RINV should be addressed regardless of the site being treated, as large observational studies in Italy and Sweden documented their significant prevalence across a broad range of curative and palliative radiation oncology practices.[3–5] This applied for tumor sites not traditionally viewed as being associated with RINV, such as the breast, skin, extremities, thorax, head and neck. Unfortunately, although these studies are large and well conducted, they stand alone and represent the vast majority of prospectively gathered RINV data outside of clinical trials, and as such their external validity is closely scrutinized by some who look to the literature to assess the prevalence of RINV.

Patterns of Practice

In addition to guidelines and literature, a powerful influence for radiation oncologists is the advice and collective experience of local and national colleagues. The ability to align one's own practice with that of one's peers is desirable, especially when considering management of uncommon tumors or treatment sequelae within this small clinical specialty. Unfortunately, the patterns of practice for the prevention and management of RINV are largely unknown when compared with other measures of supportive care in cancer, such as the highly studied and monitored rates of opioid and anticoagulation administration. However, it is generally accepted that rates of prophylaxis are low, and that often radiation oncologists wait for some degree of nausea or vomiting to develop before initiating antiemetic therapy. This notion is supported by the most recent study from the Italian Group for Antiemetic Research in Radiotherapy, which showed that only 12.4% of patients received any kind of prophylaxis, including only 41 and 28% of patients receiving treatment to the upper abdomen and brain, respectively.[3] Enblom and colleagues also found that only 17% of patients undergoing radiotherapy within their cross-sectional study had received any antiemetic therapy within 1 week of being questioned, a figure that would have included both prophylactic and rescue therapy.[5] Even more concerning is that a third of these patients still viewed their therapy as insufficient for their needs. Beyond these studies and a few small surveys,[15–17] there is little literature available that characterizes typical RINV management in daily practice.

Concurrent Radiotherapy & Chemotherapy

As the body of literature surrounding CINV antiemetic therapies is large and mature, guidelines generally recommend that these strategies be preferentially employed when chemotherapy and radiotherapy are given concurrently.[2,11,101] As such, in countries where medical oncology and radiation oncology are discrete specialties, the practitioner administering chemotherapy is often the one managing nausea and vomiting. To be sure, in general CINV are more prevalent than RINV, but radiation oncologists need to be equally engaged and responsible, especially during breaks between chemotherapy cycles when emetogenic radiotherapy is being delivered. Many antiemetic regimens for CINV last only a few days, and patients are managed afterwards with rescue therapies until the time of the next cycle. Symptoms during this transition period are usually deemed residual or 'delayed' CINV, but as daily radiotherapy would still be ongoing, acute and repetitive RINV should be suspected as well. If the antiemetic recommendation for the radiotherapy itself would otherwise be more aggressive than the rescue therapy for the chemotherapy during this period, it is more appropriate to initiate the former until the time of the next chemotherapy cycle. Similarly, if prior to any treatment the risk category of the planned radiotherapy is greater than that for the concurrent chemotherapy, guidelines generally recommend using the RINV antiemetic strategy.[2] However, this situation would be uncommon as the chemotherapy agents typically delivered with high- and moderate-risk radiotherapy have significant emetogenic potential themselves, and the CINV antiemetic strategies will almost always be initiated. This makes careful surveillance of symptoms in between cycles of utmost importance.

Knowledge Translation & Education

Most radiation oncologists are not familiar with published international antiemetic guidelines for RINV, and alternative guidelines are uncommon among most national radiotherapy associations and individual institutions. Antiemetic research is also more commonly published in palliative care or supportive care journals, which may not be regularly accessed by the majority of radiation oncologists. However, as the prevalence of RINV becomes better known, mechanisms for knowledge translation will be required to meet the educational needs of practitioners. Aside from being unaware of the relevant literature, some well-known barriers to physician adherence to international practice guidelines[18] that probably apply to the RINV setting include: a perceived lack of applicability to one's own country or patients, concerns of cost–effectiveness, concerns with rigidity of application or a challenge to one's own practice autonomy, or concerns that the recommended guidelines will not produce the desired outcome. If national associations or individual institutions were able to adapt the larger international guidelines to their own needs and settings, many of these concerns could be addressed and more radiation oncologists would accept and implement the adapted guidelines. As these processes become formalized and practised, they would become efficient and safe, which would also allay some other barriers to implementing RINV guidelines, such as the perception of not having enough time to address RINV, a lack of organizational resources or a perception of increased malpractice liability due to the use of new medications.[18] On a larger scale, consideration could also be given to consolidating the number of available international guidelines; they are all based on the same relatively small amount of literature, their committees are regularly populated by the same small group of experts and the similarities in management recommendations outnumber the disparities.

Perhaps the greatest and most longstanding impact on RINV management could be made within residency training programs. Although the demands on the radiation oncology trainee are great, palliative care and symptom control are now recognized as priorities within program curricula. Mandatory didactic and clinic-based teaching about RINV prevalence and management should be included with more commonly administered teachings on issues such as pain control and skin care. By the time of graduation, all trainees should be familiar with published guidelines for RINV antiemetic therapy, and they should have a customized approach to RINV management appropriate for their own practice environment and the financial realities of their patients and third-party payers.

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