Ietje Perfors

125 Compared to the literature, the number of patient-initiated GP contacts after diagnosis was high. In previous studies, which aimed to involve the GP in cancer care, the uptake of interventions was generally between 27% and 60%, as compared to more than 80% in our intervention group. 28–30 Even though we did not find a beneficial effect on the SDM process, the TOC may have an effect on the second aim of the TOC: continuity of primary care. On the short term, patients visited their GP more often in the intervention arm compared to the control arm. Results on continuity of primary care along the cancer care continuum will be published elsewhere. This study has several strengths and limitations. The present study contributes evidence from a pragmatic, well powered randomised controlled trial to the scarce knowledge on SDM interventions for curative cancer treatment involving the GP. Another strength is the full access to the free text and coded routine care data from the EMR of each GP practice, therefore protocol adherence could be assessed. A limitation is that breast cancer patients are overrepresented, which might make the results less generalizable to the total cancer patient population. 31 Over-representation of breast cancer is often seen in cancer research, 32 probably due to the high incidence of breast cancer, and the fact that the breast cancer care path is usually highly structured, which facilitates recruitment. Also, our study focuses on cancer patients treatedwith curative intent and findings cannot be generalised to those treated with palliative intent, because the SDM process and the added value of the GP may well be different. This is supported by a recent non-controlled study, which suggested that patients and healthcare workers (GPs and treating physicians) experienced improvements in the SDM process after implementing a similar TOC, among palliatively treated cancer patients. 33 One reason for a potential difference in effect is that curatively treated patients might not always experience having a treatment choice. 34, 35 In addition, 66 (19.3%) of the eligible patients were not included in our study because they expressed “no wish for extra guidance” or “GP related” reasons. This selection resulted in a study population whose wish for additional contact with their GP may be relatively strong. Furthermore, patients and healthcare providers could not be blinded due to the nature of the intervention, whichmight have influenced the outcomes. Moreover, we were not able to assess which actor or actors delayed the planning of the TOC. In 5