To refresh clinical diagnostic dilemmas in patients presenting with symptoms resembling to those of parkinsonism, to report rare association of colon cancer and paraneoplastic stiff person syndrome (SPS), and to draw attention on the possible correlation of capecitabine therapy with worsening of paraneoplastic SPS. Case report of the patient with paraneoplastic SPS due to colon cancer that was misdiagnosed as idiopathic Parkinson's disease (iPD), whose symptoms worsened after beginning adjuvant capecitabine chemotherapy. We describe a 55-year-old woman with subacute onset of symmetrical stiffness and rigidity of the truncal and proximal lower limb muscles that caused lower body bradykinesia, gait difficulties, and postural instability. Diagnose of iPD was made and levodopa treatment was initiated but failed to provide beneficial effect. Six months later, colon cancer was discovered and the patient underwent surgical procedure and chemotherapy with capecitabine thereafter. Aggravation of stiffness, rigidity, and low back pain was observed after the first chemotherapy cycle and capecitabine was discontinued. Furthermore, levodopa was slowly discontinued and low dose of diazepam was administered which resulted in partial resolution of the patient's symptoms. Paraneoplastic SPS is rare disorder with clinical features resembling those of parkinsonian syndrome and making the correct diagnosis remains a challenge. The diagnosis of parkinsonian syndrome should be re-examined if subsequent examinations discover an associated malignant process. Although it remains unclear whether the patients with history of SPS are at the greater risk for symptoms deterioration after administration of capecitabine, clinicians should be aware of capecitabine side effects because recognition and appropriate management can prevent serious adverse outcomes.

Introduction: There are no recommended biomarkers to identify patients with refractory metastatic colorectal cancer (mCRC) who would benefit the most from trifluridine/tipiracil (TTP). The exploratory analysis of the RECOURSE trial revealed that patients with low tumor burden and indolent disease derive greater benefit in terms of both progression-free survival (PFS) and overall survival (OS). Nevertheless, the final answer on the TTP real impact on the well-being of patients with late-stage mCRC will come from real-world data. Methods: The aim of this retrospective exploratory study was to investigate the effectiveness of TTP in mCRC with regard to the duration of standard treatment and other influencing variables. The study included 260 patients from the three largest Croatian oncology centers who began treatment with TTP in the third or fourth line between 2018 and 2020. Results: The median OS and PFS for the entire cohort were 6.53 and 2.50 months, respectively. Patients with more aggressive disease, defined as those whose time to progression on the first two lines of standard therapy was less than 18 months, had significantly shorter PFS (2.40 vs. 2.57 months, hazard ratio [HR] 1.34, 95% confidence interval [CI]: 1.03–1.84). There was also a tendency toward shorter OS (6.10 vs. 6.30 months, HR 1.32, 95% CI: 0.99–1.78) but without statistical significance. Patients with ECOG PS 0, without liver metastases, and with RAS mutation had both longer OS and PFS. No influence was detected from other variables including age, sex, primary tumor location, and tumor burden. Conclusion: With regard to the results of the previously conducted trials, the study concludes that indolent disease, good general condition, and absence of liver metastases are positive predictive factors for TTP treatment.