Introduction: Colorectal cancer (CRC) is a significant global health concern, with rising incidence in younger populations. Adjuvant chemotherapy using FOLFOX regimens is standard for locally advanced CRC, but the optimal treatment duration (3 vs. 6 months) remains debated. This study aims to analyse disease-free survival (DFS) outcomes in early-onset CRC patients receiving 3 versus 6 months of FOLFOX therapy to inform personalised treatment protocols. Methods: This observational retrospective cohort study investigated patients diagnosed with locally advanced early-onset CRC at Dr Moewardi Hospital between January and December 2024. Twenty patients were selected via consecutive sampling, with 10 receiving 3 months and 10 receiving 6 months of adjuvant FOLFOX chemotherapy. Data were collected from medical records, and DFS was evaluated over one year. Statistical analyses were performed using SPSS, with the Kaplan-Meier method used for univariate survival-rate analysis and the log-rank test to compare variable groups. Results: The majority of patients in both groups were aged 35–49 years. The incidence of metastasis was slightly higher in the 6-month group (20% vs. 10%), but the difference was not statistically significant (p = 0.584). One-year survival rates were similar in both groups (above 90%). Conclusion: This study found no significant difference in metastasis incidence or disease-free survival between locally advanced early-onset colorectal cancer patients receiving 3 months versus 6 months of adjuvant FOLFOX therapy. This suggests that a shorter chemotherapy duration may be a viable option in certain cases.

Isolated splenic metastasis from colorectal cancer (CRC) is extremely rare, occurring in only 1.2–7.1% of cases, due to the spleen’s strong immune surveillance, lack of afferent lymphatic drainage, and unique blood flow. While metastasis typically spreads to the liver and lungs, haematogenous dissemination to the spleen can occur, though the exact mechanism remains unclear. Most cases are asymptomatic and discovered incidentally through imaging or rising carcinoembryonic antigen (CEA) levels. Treatment options include systemic chemotherapy, splenectomy, or a combination, depending on disease extent and patient condition. This study reports two cases of sigmoid colon adenocarcinoma initially treated with curative surgery and six months of FOLFOX chemotherapy. Both patients showed no initial metastasis but later presented with rising CEA levels (140 ng/mL). CT scans revealed isolated splenic metastases without other systemic involvement. They underwent an additional six months of chemotherapy, achieving stable disease with no complications. These cases highlight the importance of close surveillance and suggest that systemic chemotherapy alone may be a viable alternative to splenectomy in select patients.