What it takes to reduce sitting at work: a pilot study on the effectiveness and correlates of a multicomponent intervention.

OBJECTIVE: This study aimed to assess the feasibility and effects of a simple-to-implement multicomponent intervention to reduce sedentary time of office workers. METHODS: Six groups of eight to ten office workers took part in the two-week Leicht Bewegt intervention. Participants completed questionnaires at baseline (T0, n = 52), after 2 weeks (T1, n = 46), and after 5 weeks (T2, n = 38), including subjective sedentary measures and social-cognitive variables based on the health action process approach (HAPA). Objective sedentary measures were obtained using activPAL trackers. RESULTS: The intention to reduce sedentary behavior during work increased significantly from T0 to T1. Participants' objective and subjective sitting time decreased significantly from T0 to T1, corresponding to an average decrease per 8-h-workday of 55 min (d = - .66) or 74 min (d = - 1.14), respectively. This reduction persisted (for subjective sitting time) at T2 (d = - 1.08). Participants indicated a high satisfaction with the intervention. CONCLUSIONS: The Leicht Bewegt intervention offers a feasible and effective opportunity to reduce sedentary behavior at work. Randomized controlled trials including longer follow-up time periods are needed to validate its benefits in different workplaces.

Determinants of physical activity during cancer treatment: a longitudinal exploration of psycho-cognitive variables and physician counseling.

Individuals with cancer are recommended to engage in regular physical activity (PA) even during cancer therapy. The aim of this study was to explore how patient-reported physician PA counseling influences their PA intention and behavior in addition to psycho-cognitive determinants derived from the theory of planned behavior (TPB). A longitudinal study during cancer treatment was conducted among N = 115 patients with breast, prostate, or colorectal cancer (Mage = 58.0, SD = 11.5; 55.7% female). The median time since diagnosis was 2 months, and 19.1% were diagnosed with metastases. Participants provided information on PA counseling by their physicians and on psycho-cognitive variables of the TPB at three measurement points. Additionally, they wore accelerometers for seven days at baseline and three months later. Nearly half of participants (48%) reported basic PA counseling and 30% reported in-depth PA counseling. Patients in poorer health and with lower education reported significantly less in-depth counseling. In addition to patient self-efficacy in performing PA, only in-depth physician PA counseling, but not basic physician counseling, predicted intention for PA four weeks later. Patients' PA three months after baseline was predicted by patients' PA at baseline and their intention for PA. Overall, the PA level at baseline was identified as the most important predictor of PA three months later. Nevertheless, physicians seem to have the ability to increase their cancer patients' intention for PA by in-depth counseling.

Better not resting: Carving out attitudes and their associations with physical activity in people with cancer.

OBJECTIVE: Evidence on the benefits of physical activity (PA) during cancer has caused a paradigm shift from people with cancer being advised to save energy (rest paradigm) to guidelines recommending them to engage in regular PA (activity paradigm). This study examined the rest and the activity paradigm among people with cancer based on the theory of planned behaviour (TPB). METHODS: A cross-sectional survey was completed by N = 1244 people (58% women; M = 59.95 years) with breast, prostate and colorectal cancer, including 15 items on rest and activity attitudes. To explain the intention to engage in PA, hierarchical regression analyses were calculated. RESULTS: The two-dimensional structure of attitudes (rest and activity) was confirmed. The agreement with the activity paradigm (M = 4.11; SD = 0.78) was higher compared to the rest paradigm (M = 2.56; SD = 0.78, p < .001). The TPB was an appropriate model to explain the intention to engage in PA (R2 = .59), showing that the activity paradigm, but not the rest paradigm, was significantly associated with participants' intention for PA. CONCLUSION: Results indicate that the paradigm shift has successfully reached attitudes of people with cancer. Interventions focusing on the benefits of PA rather than addressing rest cognitions promise higher effectiveness in affecting PA levels. CLINICAL TRIAL REGISTRATION NUMBER: NCT02678832.

Impact and Determinants of Structural Barriers on Physical Activity in People with Cancer.

BACKGROUND: A better understanding of the role of structural barriers for physical activity (PA) after a cancer diagnosis could help to increase PA among people with cancer. Thus, the present study aimed to identify determinants of structural barriers to PA in people with cancer and investigate the association between structural barriers and insufficient post-diagnosis PA, taking different PA change patterns into account. METHODS: A total of 1299 people with breast, prostate, or colorectal cancer completed a questionnaire assessing their socio-demographic and medical characteristics, pre- and post-diagnosis PA, and perceived PA impediment by seven structural barriers. Regression analyses were used to investigate determinants of the perception of structural barriers and to examine the association between structural barriers and insufficient post-diagnosis PA, also with regard to different pre-diagnosis PA levels. RESULTS: Overall 30-60% of participants indicated to feel impeded by structural barriers. The analyses revealed a younger age, higher BMI, lower educational level, no current work activity, co-morbidities, and lacking physicians' exercise counseling as significant determinants of the perception of structural barriers. Individuals reporting stronger impediments by structural barriers were significantly less likely to be meeting PA guidelines post-diagnosis, particularly those with sufficient pre-diagnosis PA levels. CONCLUSIONS: The study highlights the need for tailored PA programs for people with cancer as well as for more guidance and support in overcoming structural barriers to improve PA behavior. The study has been registered under NCT02678832 at clinicaltrials.gov on February 10th 2016.

The association between physicians' exercise counseling and physical activity in patients with cancer: Which roles do patients' satisfaction and previous physical activity levels play?

OBJECTIVES: The purpose of this study was to examine the association between physicians' exercise counseling and post-diagnosis physical activity (PA) in patients with cancer by investigating the mediating role of patients' satisfaction with exercise counseling as well as the moderating role of patients' previous PA. METHODS: The study sample consisted of 1002 people with cancer (503 breast, 265 prostate, and 234 colorectal cancer). Participants reported their pre- and post-diagnosis moderate-to-vigorous PA (MVPA) levels, indicated whether their physician had covered different steps of exercise counseling as defined by the 5A framework (Assess, Advise, Agree, Assist, and Arrange) and rated their satisfaction with exercise counseling. A conditional process analysis was used to determine the direct and indirect effects of counseling on post-diagnosis MVPA through satisfaction at different levels of pre-diagnosis MVPA. RESULTS: Physicians' exercise counseling was associated with post-diagnosis MVPA in patients with cancer. However, the association differed by patients' pre-diagnosis MVPA (P = .039). While counseling was directly associated with higher post-diagnosis MVPA for individuals with low pre-diagnosis MVPA (CI: 0.02-0.20, P = .014), the effect was mediated through satisfaction with exercise counseling for previously highly active individuals (Boot CI: 0.01-0.08). CONCLUSIONS: Our findings emphasize the relevance of physicians' exercise counseling for PA in patients with cancer. However, the results indicate that in order to effectively influence patients' PA, it appears important to provide a comprehensive counseling that is adjusted to the patients' exercise experiences.

Change patterns and determinants of physical activity differ between breast, prostate, and colorectal cancer patients.

PURPOSE: The purpose of this study was to examine and compare pre- to post-diagnosis change patterns of physical activity (PA) among breast, prostate, and colorectal cancer patients. Moreover, the study aimed to investigate sociodemographic and medical determinants of post-diagnosis PA and to identify patient subgroups at increased risk of inactivity. METHODS: A total of 912 cancer patients (457 breast, 241 prostate, 214 colorectal cancer) completed a questionnaire assessing their pre- and post-diagnosis PA behavior, and sociodemographic and medical variables. Age-adjusted regression and classification tree analyses were used to investigate PA determinants and detect subgroups that were most likely to meet or not meet PA guidelines. RESULTS: Across cancer types, we found that PA yet decreased from pre- to post-diagnosis, but that 54.1% of participants still reported to be meeting PA guidelines after the diagnosis. While post-diagnosis PA was strongly affected by previous PA behavior among individuals of all patient groups, other sociodemographic and medical determinants played different roles depending on cancer type. The results yielded that previously active, longer diagnosed patients with higher education levels were most likely to be meeting PA guidelines post-diagnosis, whereas specifically previously inactive prostate cancer patients had an increased likelihood of insufficient activity. CONCLUSIONS: An encouragingly high number of cancer patients indicated sufficient PA levels. For those having difficulties to maintain or adopt PA post-diagnosis, interventions should be tailored to the specific characteristics of each cancer type, as different factors are associated with PA for each patient group.

Dislocated spots and triple splittings of natural rainbows generated by large drop distortions, oscillations, and tilts.

For an accurate modeling of natural rainbows, it is necessary to take into account the flattened shape of falling raindrops. Larger drops do also oscillate, and their axes exhibit tilt angles with respect to the vertical. In this paper, I will discuss two rare rainbow phenomena that are influenced by these effects: bright spots belonging to various rainbow orders, but appearing at remarkable angular distances from their traditional locations, as well as triple-split primary rainbows. While the former have not been observed in nature so far, the latter have been documented in a few photographs. This paper presents simulations based on natural drop size distributions using both a geometric optical model, as well as numerically calculated Möbius shifts applied to Debye series data.

Light and Color in Nature 2020: introduction to the feature issue.

This feature issue on Light and Color in Nature focuses on the interplay of light with the landscape and other naked-eye phenomena and describes a wide range of natural optical phenomena that can be seen in our natural environment. Results are reported on the experimental and theoretical investigations undertaken to improve understanding of these phenomena.

The Influence of Cancer Patient Characteristics on the Recommendation of Physical Activity by Healthcare Professionals.

BACKGROUND: Although physical activity (PA) is beneficial for patients with cancer, healthcare professionals (HCP) still scarcely recommend it. This study aimed to determine how HCP' sociodemographic and professional characteristics and their subjective assessments of patient characteristics are associated with their PA recommendations to patients with cancer. METHODS: A cross-sectional survey (paper-pencil or online) was completed by 929 HCP (159 general practitioners, 382 specialized physicians, and 388 oncology nurses). The survey collected information on HCP' sociodemographic and professional characteristics, PA recommendation frequency, and the likelihood of 13 patient characteristics influencing PA recommendations (on a 7-point Likert scale). RESULTS: Descriptive results showed that 37.6% of HCP indicated often recommending PA and 41.7% indicated routinely recommending PA. More professional experience was associated with a higher reported PA recommendation frequency among specialized physicians and oncology nurses. Patient characteristics could be assigned to three higher-level categories. Characteristics from the categories "medical side effects" and "low affinity for PA" were more frequently judged by HCP as reasons for recommending PA and characteristics belonging to "indicators of poor general health" as reasons for not recommending PA. In all professional groups, the inclusion of patient characteristics resulted in additional variance explained in the prediction of a routine PA recommendation. CONCLUSIONS: HCP in this study reported that they frequently recommend PA to patients with cancer. However, HCP consider cancer patient characteristics to influence their decision whether to recommend PA. Future research and interventions should aim to enable HCP to provide adequate PA recommendations to patients with cancer having different characteristics.

To rest or not to rest-Health care professionals' attitude toward recommending physical activity to their cancer patients.

OBJECTIVE: While in the past cancer patients were advised to rest, recent research revealed various beneficial effects of physical activity, including increased treatment tolerability during cancer treatment and prolonged survival, which has led to a paradigm shift in relevant guidelines. This study examined if this paradigm shift from rest to activity has been consolidated in health care professionals' (HCP') attitude. It was investigated if the two dimensions of attitude (rest and activity) are endorsed empirically within the theory of planned behavior (TPB). Differences between physicians and nurses were examined. METHODS: Five hundred forty seven physicians and 398 nurses treating breast, prostate, or colorectal cancer patients completed a cross-sectional questionnaire. To assess attitude toward physical activity during cancer treatment, we developed a 15-item scale, which included original statements of HCP. TPB variables were assessed. RESULTS: A factor analysis revealed the proposed distinction of attitude into two dimensions. The activity-paradigm was stronger represented in HCP' attitude compared with rest-paradigm (Mactivity-paradigm  = 4.1 versus Mrest-paradigm  = 2.7, p < 0.001). Additionally, the activity-paradigm had higher exploratory power in explaining intention to recommend physical activity in cancer patients. However, the rest-paradigm was able to explain intention to recommend physical activity over and above activity-paradigm (ΔR2  = 0.05). Nurses had higher scores on the rest-paradigm than physicians. CONCLUSIONS: The activity-paradigm has already been consolidated in HCP' minds. However, the rest-paradigm is still present in the daily routine of oncology physicians and nurses. Addressing concerns and insecurities related to supporting cancer patients in maintaining or building up a physically active lifestyle is a very important educational task.

Which self-management strategies do health care professionals recommend to their cancer patients? An experimental investigation of patient age and treatment phase.

This vignette based study aimed to examine recommendations of health care professionals (HCPs) in promoting self-management strategies to cancer patients. Nine-hundred-forty-two physicians and nurses were asked to (1) indicate if they would recommend self-management strategies to a vignette cancer patient, and (2) to specify those in an open format. Vignettes included a manipulation of patient age (60 vs. 75 years) and treatment phase (currently treated versus treatment completed). Six categories emerged through coding a total of 2303 recommendations: physical activity (71.8%), nutrition (64.3%), psychological support (36.7%), medical support (29.2%), conscious living (17.2%) and naturopathy (12.3%). While psychological support was particularly recommended during treatment, physical activity was more frequently recommended after completion of treatment. Results suggest that HCPs recommend a variety of self-management strategies besides standard medical treatment. Patient's treatment phase and age seem to partly influence recommendation behavior, potentially indicating insecurities regarding acute treatment situations and age-related stereotypes.

Are healthcare professionals being left in the lurch? The role of structural barriers and information resources to promote physical activity to cancer patients.

PURPOSE: Although many cancer patients benefit from physical activity (PA), healthcare professionals (HCP) still do not promote it routinely. Including different groups of HCP, this study aimed to examine how structural barriers are perceived as impeding by HCP for promoting PA to cancer patients, how the perceptions of structural barriers are associated with promoting PA, and how HCP react to information resources. METHODS: A total of 287 physicians in outpatient care, 242 physicians in inpatient care, and 388 oncology nurses completed our questionnaire (paper-pencil or online). Participants assessed nine different structural barriers (on a 4-point Likert Scale) and reported their PA promotion frequency. Further, they could request three different kinds of information resources about PA in oncological settings. RESULTS: Across professional groups, more than 70% of HCP indicated that they promoted PA to their cancer patients often or routinely. Oncology nurses indicated that they were more impeded in promoting PA by six structural barriers than physicians (all p < .01). "Not enough time per patient" and "lack of an expert contact person" were associated with a reduced PA promotion in two professional groups (all p < .05). Information resources were requested by 69.5% of the participants: mostly physicians working in outpatient care and especially by those perceiving structural barriers. CONCLUSIONS: Although a big proportion of HCP reported that they frequently promoted PA, our findings suggest that HCP still perceive structural barriers. The perception and influence of structural barriers differed between professional groups, pointing to the importance of profession specific guidance.

What hinders healthcare professionals in promoting physical activity towards cancer patients? The influencing role of healthcare professionals' concerns, perceived patient characteristics and perceived structural factors.

Despite a large body of evidence showing that physical activity (PA) is beneficial to patients with cancer, healthcare professionals (HCPs) are promoting it too scarcely. Factors that hinder HCPs from promoting PA have remained understudied so far. Using a qualitative approach, this study aimed at a comprehensive description of influencing factors for HCPs' PA promotion behaviour and at identifying the reasons and mechanisms behind them. Semi-structured interviews with 30 HCPs were undertaken with a focus on concerns, patient characteristics and structural factors. Answers were analysed using thematic analysis. Results revealed that HCPs had concerns regarding a physical overexertion and psychological stress for patients with cancer. A patient's physical condition and the assumed interest in PA, often derived from former PA, turned out to be the most crucial patient characteristics influencing if PA is addressed. Structural factors relevant for PA promotion pertained to in-house structures, HCPs' workload, timing and coordination, information material for HCPs and patients and availability of exercise programs. In conclusion, this study revealed undetected concerns of HCPs and underlined the relevance of patient characteristics and structural conditions for HCPs' PA promotion towards patients with cancer. A broader perspective is needed to assess these factors in their influence on HCPs' PA promotion.

Advanced analysis of domain walls in Mg doped LiNbO3 crystals with high resolution OCT.

The structure of domain walls (DW) in ferroelectric media is of great interest as this material is used for frequency doublers and other applications. We show that the structure of the DWs can nicely be visualized by high resolution optical coherence tomography (OCT). While the high group refractive index of lithium niobate allows a resolution much better than 1 µm, the large dispersion can blur the image and has to be compensated. Therefore, we developed an adaptive dispersion compensation algorithm based on maximizing the intensity of the DWs. By measuring a group of DWs, the mean period of the DWs could be measured with an accuracy of less than 10 nm differentiating samples with only 30 nm distinct periods. By analyzing the peak position, amplitude and phase shift within a DW, we were able to determine steps in the DW of only 50 nm. Furthermore, the inclined course of the DWs in a fan-shaped frequency doubler could be displayed. Therefore, we conclude that OCT is able to provide valuable information about the structure of domain walls in periodically poled lithium niobate (PPLN).

Bottom-Up Assembly of Molecular Nanostructures by Means of Ferroelectric Lithography.

Here, we report on the photochemical deposition of Rhodamine 6G (Rh6G) and Alexa647 molecules from aqueous and methanolic solution along 180° ferroelectric (FE) domain walls (DWs) of z-cut lithium niobate (LNO) single crystals. Molecules and FE domains were investigated by means of dynamic-mode AFM, piezoresponse force microscopy (PFM), and confocal scanning fluorescence microscopy. A high deposition affinity for 180° DWs on the LNO surface is observed, leading to the formation of molecular nanowires. Additionally, a more complex deposition pattern for Rh6G adsorbed to the domain areas of freshly poled samples was equally observed, being associated with the DW dynamics. These results are explained by considering contributions from screening-charge-dependent photochemistry as confined to the DWs, UV-induced DW motion, and transient electrostatic fields arising from the metastable defect distribution shortly after poling. Hence, tuning these effects offers the possibility for accurately controlling the complex bottom-up assembly of functional molecular nanostructures through domain-structured ferroelectric templates.

Light scattering from sessile water drops and raindrop-shaped glass beads as a validation tool for rainbow simulations.

The shape deviation of falling raindrops from exact spheres is known to affect the appearance of natural rainbows, e.g., by enhancing the visibility of supernumerary arcs around the top or by creating branching effects known as "twinned rainbows." To check the accuracy of numerical optical models for rainbow scattering from such nonspherical drops, two simple and low-cost experiments are presented in this paper: (1) sessile, i.e., sitting, drops on ultrahydrophobic surfaces, and (2) glass beads in the shape of falling raindrops. The experimental results are compared to polarization-resolved Monte Carlo ray-tracing simulations, with special emphasis on circular polarization, which results from total internal reflections in these nonspherical scatterers.

Observation, analysis, and reconstruction of a twinned rainbow.

A photograph of a twinned rainbow, obtained on 11 May, 2012, in Dresden, Germany, is precisely calibrated with respect to lens projection and camera orientation. Since the twinning was only located in a part of the picture, it was possible to read out the red-green-blue intensity data from both a twinned and nontwinned position of the rainbow. These data were fitted with modeled spectra for polydisperse drop distributions, which were calculated with a Debye series algorithm and shifted in the scattering angle to account for the nonspherical shape of natural raindrops. The shift data were acquired from raytracing through realistic raindrop shapes modeled by two conjoined half-spheroids of different oblateness. Effective drop size distributions along the line of sight are derived from the fit for the two sampling positions and used to generate a true-color simulation of the original photograph. By this, the optical determination of physical rainfall properties is demonstrated.

Providing the basis for a patient-centred and effective screening for cancer-related fatigue (MERLIN study): design of a longitudinal observational study.

INTRODUCTION: Cancer-related fatigue (CRF) is a frequent and burdensome sequela of cancer and cancer therapies. It can persist from months to years and has a substantial impact on patients' quality of life and functioning. CRF is often still not adequately diagnosed and insufficiently treated. According to guideline recommendations, patients should be routinely screened for CRF from cancer diagnosis onwards. We will investigate how an effective screening should be designed regarding timing, frequency, screening type and cut-off points. METHODS AND ANALYSIS: MERLIN is a longitudinal observational study that will include 300 patients with cancer at the beginning of cancer therapy. The main study centre is the National Center for Tumour Diseases Heidelberg, Germany. Patients answer five items to shortly screen for CRF at high frequency during their therapy and at lower frequency during the post-treatment phase for 18 months. Further, CRF is assessed at wider intervals based on the Cella criteria, the Brief Fatigue Inventory impact scale, the quality of life fatigue questionnaire (QLQ-FA12) and the fatigue and cognitive items of the quality of life core questionnaire (QLQ-C30), both of the European Organisation for Research and Treatment of Cancer. Important psychological, socio-demographical or medical factors, which may exacerbate CRF are assessed. All assessments are performed online. Receiver operating curves, areas under the curve, sensitivity, specificity, positive and negative predictive values and likelihood ratios will be calculated to determine optimal short screening modalities. ETHICS AND DISSEMINATION: The study was approved by the ethics committee of the Medical Faculty of the Heidelberg University, Germany (approval number: S-336/2022). Written informed consent is obtained from all participants. The study is conducted in full conformance with the principles of the Declaration of Helsinki. Results will be published in peer-reviewed scientific journals, presented at conferences and communicated to clinical stakeholders to foster the implementation of an effective CRF management. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov; registration number: NCT05448573.

Whole Breast Irradiation in Comparison to Endocrine Therapy in Early Stage Breast Cancer-A Direct and Network Meta-Analysis of Published Randomized Trials.

BACKGROUND: Multiple randomized trials have established adjuvant endocrine therapy (ET) and whole breast irradiation (WBI) as the standard approach after breast-conserving surgery (BCS) in early-stage breast cancer. The omission of WBI has been studied in multiple trials and resulted in reduced local control with maintained survival rates and has therefore been adapted as a treatment option in selected patients in several guidelines. Omitting ET instead of WBI might also be a valuable option as both treatments have distinctly different side effect profiles. However, the clinical outcomes of BCS + ET vs. BCS + WBI have not been formally analyzed. METHODS: We performed a systematic literature review searching for randomized trials comparing BCS + ET vs. BCS + WBI in low-risk breast cancer patients with publication dates after 2000. We excluded trials using any form of chemotherapy, regional nodal radiation and mastectomy. The meta-analysis was performed using a two-step process. First, we extracted all available published event rates and the effect sizes for overall and breast-cancer-specific survival (OS, BCSS), local (LR) and regional recurrence, disease-free survival, distant metastases-free interval, contralateral breast cancer, second cancer other than breast cancer and mastectomy-free interval as investigated endpoints and compared them in a network meta-analysis. Second, the published individual patient data from the Early Breast Cancer Trialists' Collaborative Group (EBCTCG) publications were used to allow a comparison of OS and BCSS. RESULTS: We identified three studies, including a direct comparison of BCS + ET vs. BCS + WBI (n = 1059) and nine studies randomizing overall 7207 patients additionally to BCS only and BCS + WBI + ET resulting in a four-arm comparison. In the network analysis, LR was significantly lower in the BCS + WBI group in comparison with the BCS + ET group (HR = 0.62; CI-95%: 0.42-0.92; p = 0.019). We did not find any differences in OS (HR = 0.93; CI-95%: 0.53-1.62; p = 0.785) and BCSS (OR = 1.04; CI-95%: 0.45-2.41; p = 0.928). Further, we found a lower distant metastasis-free interval, a higher rate of contralateral breast cancer and a reduced mastectomy-free interval in the BCS + WBI-arm. Using the EBCTCG data, OS and BCSS were not significantly different between BCS + ET and BCS + WBI after 10 years (OS: OR = 0.85; CI-95%: 0.59-1.22; p = 0.369) (BCSS: OR = 0.72; CI-95%: 0.38-1.36; p = 0.305). CONCLUSION: Evidence from direct and indirect comparison suggests that BCS + WBI might be an equivalent de-escalation strategy to BCS + ET in low-risk breast cancer. Adverse events and quality of life measures have to be further compared between these approaches.

The Relationship between Exercise Self-Efficacy, Intention, and Structural Barriers for Physical Activity after a Cancer Diagnosis.

Previous research has shown that structural barriers negatively influence the physical activity (PA) behavior of cancer patients, but underlying mechanisms are unclear. The aim of the current study was to explore the potential mediating role of social-cognitive factors, namely PA self-efficacy and PA intention in this context. A total of 856 cancer patients completed a questionnaire on sociodemographic and medical characteristics, pre- and post-diagnosis PA, PA self-efficacy, PA intention, and PA impediment by structural barriers. A serial mediation model was used to test whether the association between structural barriers and post-diagnosis PA was mediated by PA self-efficacy and/or PA intention, in the overall sample and in subsamples defined by individuals' pre-diagnosis PA. The results confirmed that structural barriers were not directly (95%CI [-0.45; 0.10]) but indirectly associated with post-diagnosis PA. Higher impediment by structural barriers decreased the likelihood of sufficient post-diagnosis PA via lower PA self-efficacy (95%CI [-0.25; -0.06]) and via the serial pathway of lower PA self-efficacy and lower PA intention (95%CI [-0.19; -0.05]). Investigating differences in these mediations by pre-diagnosis PA yielded significance only among previously active cancer patients. Both structural barriers and PA self-efficacy might hence be relevant target points for interventions aiming to improve PA behavior, especially among pre-diagnosis active cancer patients.