Endometrial cancer is the 4th most commonly diagnosed cancer in women [44], and with 5-year survival exceeding 90% [1] there is a large population of survivors. However, endometrial cancer survivors are more likely to die from CVD then their cancer [4]. Furthermore, unlike many other cancers, endometrial cancer incidence is growing with more cases being diagnosed every year likely due to the increasing obesity epidemic, with many shared risk factors between endometrial cancer and obesity [45, 46]. Factors that contribute to obesity risk (i.e., insulin resistance) are also associate with endometrial cancer risk [47]. However, risk of death from CVD is greater than risk of death from endometrial cancer five years after diagnosis with an age-adjusted standardized mortality ratio of 8.8 (95% confidence interval 8.7–9.0) [3, 48]. In a Surveillance, Epidemiology, and End Result (SEER) study, Ward et al. [3], report that over time the probability of CVD increases in endometrial cancer survivors and calls for investigation into potential survivorship interventions aimed at targeting CVD risk reduction.

An estimated 80% of survivors of endometrial cancer are overweight/obese and spend a large amount ($>$8 hours per day) of time sedentary [28, 49], posing a significant threat to their well-being and health-related quality of life [50]. However, existing literature investigating SB in endometrial cancer survivors is currently limiting by data only including questionnaire (not objective accelerometry data) [51]. The majority of survivors exhibit the motivation to change these patterns of behavior in wake of their cancer diagnosis [50] but only about half of cancer survivors in general receive consultation on improving activity behaviors [52]. Furthermore, it is not clear why endometrial cancer survivors are sedentary. There is a moderate level of evidence linking sitting time and endometrial cancer [53], but significantly less evidence pertaining to why endometrial cancer survivors are sedentary and the behavioral determinants influencing activity behaviors. Information regarding SB in endometrial cancer survivors is currently limited by the majority of the evidence being cross-sectional survey data. More research is needed to better understand this multidimensional behavior in endometrial cancer survivors as each cancer survivorship group has unique needs depending on the biology of the disease, patient characteristics, and effects of treatment [54]. For example, early-stage endometrial cancer is curative with surgery yet patients (who are likely obese and have multiple comorbidities) [54] need survivorship interventions improve lifestyle behaviors to improve cardiometabolic disease burden.

Despite substantial evidence of the benefits of physical activity such as CVD risk reduction and disease prevention [55], participation is extremely low. An estimated 80% of US adults do not meet recommended physical activity levels ($\ge$150 mins of moderate-to-vigorous intensity physical activity per week) [56] likely due to barriers such as lack of time, access, or knowledge [57, 58]. One study of N = 120 early-stage endometrial cancer survivors found that 88.3% were physically inactive [54] despite physical activity being correlated with quality of life in endometrial cancer survivors [59]. We hypothesize that the existing physical activity interventions do not account for the specific challenges that survivors face such as low physical function, obesity, fatigue, and neuropathy (Table 2) [60, 61, 62, 63, 64]. Participation in physical activity is even lower in clinical populations such as those with endometrial cancer who are burdened with barriers and challenges from cancer treatment such as low physical function, pain, obesity, neuropathy, and fatigue [60, 61, 62, 63, 64]. As physical inactivity and SB are distinct risk factors [65], individuals meeting recommended guidelines for physical activity engagement (150 min/week) are not fully protected from the detrimental cardiovascular effects associated with SB.

There is a growing presence of both movement behaviors (physical activity and SB) in public health guidelines [66]. However, the recommendations for reducing SB are far less specific vaguely stating “sit less and move more” [66]. There are critical gaps in SB interruption recommendations that need to be filled including frequency, intensity, time (duration), and type (modality such as standing or walking). Our best evidence for breaking up SB to reduce CVD risk includes interruptions every 20–30 minutes using a light intensity activity like walking for 2–5 minutes [67]. However, existing evidence does not account for special populations, like endometrial cancer survivors, who may need tailored recommendations and have greater risk for CVD [4]. For example, the ACSM physical activity guidelines provide specific recommendations for special populations like cancer survivors, who made need different SB interruption prescription (frequency, dose, type) but more SB research is needed before we have enough evidence to create such prescription. Furthermore, current guidelines do not provide recommendations addressing promotion from SB interruption to regular engagement in physical activity. The progression from reducing to SB to meeting physical activity guidelines is critical for individuals to reap the benefits of physical activity. However, current guidelines do not include progression strategies.

Despite strong evidence of endometrial cancer survivors engaging in high amounts of SB [50], there is a clear lack of interventions targeting SB reduction. Additionally, there are limited physical activity interventions targeting endometrial cancer survivors. Existing literature reports improvement in quality of life following physical activity (i.e., walking) interventions [63, 68, 69, 70], but concerningly there are frequent reports of adherence and compliance [68, 70] issues even greater than the general population. Furthermore, a qualitative study conducted by Koutoukidis et al. [71] reported endometrial cancer survivors experience many challenges and barriers to physical activity engagement (i.e., time, financial, and geographical constraints; treatment effects; obesity-related stigma social; and a lack of information/instruction) and express a clear lack of knowledge on what activity they should be trying to complete (frequency, intensity, time, and type).

In terms of SB reduction interventions, findings in individuals with obesity can guide our understanding regarding some of the unique challenges endometrial cancer survivors face. For example, Judice et al. [72] conducted a pilot study to evaluate the short-term effectiveness and feasibility of prompting SB interruption in individuals with obesity throughout the workday and during home/leisure time activities. Results indicated the intervention strategy was successful in reducing SB and increasing the amount of time spent standing/walking per day. Upon review of participant feedback, it was clear that participants responded to the prompts by increasing the length of standing/light physical activity bouts and preferred this time adjustment to more frequent interruptions in SB [72]. The authors reported behavioral resistance to more frequent sit to stand transitions. It appears participants with obesity do not prefer more frequent SB interruptions (with a shorter duration), but instead would rather increase the duration of the interruption with walking or standing (decreasing frequency of interruption). In a population of older adults, Hartman and colleagues [73], conducted a long-term (16 weeks) SB intervention study during which, the intervention was adjusted based on participant feedback to intensify coaching and support during the latter portion of the study. These adjustments ultimately led to a significant decrease in SB and increase in PA (light intensity) among individuals at high risk for CVD. A strong foundational understanding of the needs of the population is critical to support feasibility, since an intervention will only work if participants are willing to adhere to it. Design components aimed to promote long-term adherence to SB interventions in special populations (e.g., endometrial cancer survivors) are lacking and constitute a methodological pitfall common in SB intervention design and study approach. The results from Judice et al. [72] and Hartman et al. [73] emphasize that active inclusion of participant feedback is important for the development and modification of feasible interventions suited to the target population that will facilitate easy habituation and long-term adoption of the intervention [72].

Endometrial cancer survivors face many challenges to engaging in healthy movement behaviors such as low physical function [63], cancer related fatigue [60, 61], obesity [62], pain [63], and limited self-efficacy [64]. Compared to other types of cancer survivors, endometrial cancer survivors in particular engage in higher amounts of SB [53]. Endometrial cancer survivors are also highly inactive [74]. Evidence suggests that physical activity engagement provides clear benefits for CVD prevention and survivorship such as enhanced quality of life [68]. However, only an estimated 12–29% of endometrial cancer survivors meet physical activity guidelines [59, 75]. Reducing SB may be a feasible strategy to reduce CVD burden in endometrial cancer survivors because interruptions strategies such as standing or walking may be more feasible for this population that is commonly both deconditioned and overweight/obese [76]. Additionally, SB reduction likely requires fewer resources (e.g., education, cost, time) than changing other CVD related lifestyle behaviors (e.g., physical activity, diet, sleep). When aiming to improve lifestyle behavior in endometrial cancer survivors, reducing SB may be a critical first step that may lead to subsequent physical activity engagement.

As the prevalence of CVD in endometrial cancer survivors continues to increase, it is necessary to move beyond “sit less and move more” in an effort to prescribe specific guidance to reduce SB [56]. Recent research [66, 77] into preventative measures has increasingly focused on the relationship between SB and chronic disease. This includes exploring the impact of SB reduction on disease risk independent of and in conjunction with physical activity interventions. Dogra et al. [78], suggests an approach to clinical physical activity counseling that starts with reducing SB. The proposed stepwise approach recommends clinicians begin with motivational interviewing designed to assess their patients’ current SB and physical activity habits along with their motivation and ability to change said habits (Fig. 1). If clinician time constraints limit the feasibility of implementation, then perhaps they could provide a referral (i.e., to see a nutritionist and/or physical therapist) or handout such as Fig. 1 instead. However, provider recommendations regarding diet and exercise are associated with beneficial changes in cancer patients’ lifestyle behaviors [79]. For patients who are sedentary and/or do not meet physical activity guidelines, the stepwise approach [78] suggests healthcare teams (i.e., clinicians, researchers, nurses, physician assistants, physical therapists, psychologists, etc.) begin with SB counseling. Since endometrial cancer survivors face additional challenges to healthy lifestyle engagement, and individuals with obesity display behavioral resistance to frequent SB interruptions [72], we suggest the stepwise approach to increase physical activity should begin by targeting SB once per hour.

Fig. 1.

Stepwise Approach to Sedentary Behavior Reduction for Endometrial Cancer Survivors. This figure represents a worksheet that could be distributed to endometrial cancer survivors when they are waiting for their appointment to start in clinical settings. The endometrial cancer survivor will self-reflect, and shade in the circles to represent how much time they spend sitting or being physically active per day. It also gives examples of goal setting, and provides easy to follow steps to increase physcial activity by starting with sedentary behavior reduction.

The goal of stepwise SB counseling is to interrupt prolonged SB and increase the amount of sit to stand transitions (ideally, 2–5 per hour) [78]. Since changing lifestyle behaviors may be met with behavioral resistance, theoretically informed behavioral counseling approaches employing goal-setting [78] and mental contrasting [80] need to be prioritized. Increasing the duration of the interruption appears to be the first step then individuals should work to increase the frequency of the SB interruptions over time [72]. Once the individual has successfully adopted the goals of step one (increased sit to stand transitions) into their daily routine, the clinician/researcher/healthcare team member will help them move on to and through step two which involves participation in light intensity physical activity (i.e., walking, household chores, gardening, playing with pets). The third step involves a progression towards incorporating moderate physical activity (i.e., resistance training, brisk walk, jog, biking) and the fourth step involves vigorous physical activity (i.e., running, jumping, swimming, heavier resistance training). The final step includes reaching a level of cardiorespiratory and musculoskeletal fitness that is associated with positive overall health outcomes such as reduced CVD risk. In the final step, maintenance of recommended physical activity and SB reduction will be achieved. By beginning with reducing SB, the stepwise approach [78] addresses many of the most commonly cited barriers to physical activity among endometrial cancer survivors, including physical limitations to exercise, fatigue, time constraints (interrupting SB requires less time than traditional physical activity/exercise engagement), transportation (SB reduction can occur at home or at work) [56]. The stepwise approach [78] to SB reduction is also grounded in behavioral theory, potentially making it a feasible strategy to use in endometrial cancer survivors [80].

The overarching goal of research should be to inform policy that provides clear guidelines to promote health and well-being. Current guidelines for SB reduction are lacking in specificity and fail to include special populations that are at higher risk for CVD such as endometrial cancer survivors. Endometrial cancer survivors are amenable to lifestyle changes during follow-up care [17, 81]. However, these patients struggle to successfully implement lifestyle changes to improve their health-related quality of life and increase long-term survivorship. A recent study conducted by the American Society of Clinical Oncology (ASCO) found that only 56.87% of respondents reported discussion about exercise during visits to their oncologists, thus it is likely that many cancer patients are unaware of their inactivity and its impact [79]. Thus, in adapting SB and physical activity interventions for endometrial cancer survivors, it is crucial to eliminate as many of the population-specific challenges to facilitate long-term behavior change. For example, handouts and conversations with their oncologist about diet and exercise serve to educate cancer patients about PA and SB as well as direct them toward helpful resources. When researchers and clinicians design interventions utilizing the stepwise approach, behavioral theories to promote enhancing self-efficacy will likely make long-term maintenance of healthy lifestyle behaviors more feasible. A recent meta-analysis reports a significant relationship between an individual’s confidence in their ability to reduce SB and lower levels of SB (combination of objective and self-reported SB measurement) [82] suggesting that self-efficacy may be a critical factor in reducing SB in endometrial cancer survivors. Increases in self-efficacy has resulted in initiating leisure-time walking within sedentary women after and implementation intentions intervention [83].

Implementation intentions aim to promote initiation of goal-oriented behaviors, encourage behavioral maintenance when presented with unwanted obstacles, and promote accessibility and automaticity of goal-directed responses [84]. Implementation intentions (or making “if-then” plans) should be used in conjunction with mental contrasting, a self-regulatory strategy, the intended goal with realistic obstacles [84]. “If-then” plans foster sustained behavioral change by creating goal-directed behaviors and attaching them to external cues which ultimately promotes initiation and automaticity of these behaviors (i.e., “When my phone beeps three times I will stand up for 30 seconds.”). Mental contrasting is also important in creating effective implementation intentions [14] because it preemptively creates an achievement-focused mental structure for approaching adversity and promotes a goal-oriented response to unwanted influences/obstacles. These behavioral techniques should be integrated into the first step of the stepwise approach (Fig. 1) and then maintained throughout to increase physical activity by starting with SB reduction.

The lack of success in translating SB interventions from non-clinical populations to endometrial cancer survivors can be described as a result of the intention-behavior gap [85]. The gap between goal intentions and goal achievement is common problem inhibiting behavior change in all of us to some extent. The intention-behavior gap is often a result of multiple interacting factors [85]. In the case of endometrial cancer survivors, the gap between strong goal intentions—to change physical activity and/or SB—and long-term lifestyle changes is due, in large part, to a disproportionate number of obstacles that are not accounted for in typical physical activity interventions. Endometrial cancer survivors need a behavioral approach to increase self-efficacy and increase their resilience against obstacles in order to implement lifestyle behavior change. Successful integration of behavioral techniques into—properly adapted—SB interventions for endometrial cancer survivors will promote initial behavior change and progress maintenance. Therefore, we suggest a stepwise approach [78] to reduce SB will successfully lead to increased physical activity long-term compared to traditionally implementing physical activity without consideration for behavior chance to maintenance.