High FIT results in CRC patients and 1-year mortality outcomes

High fecal immunochemical test (FIT) results in colorectal cancer (CRC) patients are strongly associated with significantly worse 1-year mortality outcomes, according to the study. Below is a detailed breakdown of the key findings related to high FIT results and 1-year mortality outcomes:

### 1. **Mortality Rates in High-FIT Group (FIT ≥ 10 µg Hb/g) vs Low-FIT Group (FIT < 10 µg Hb/g):**

• **All-cause mortality:**
• Elevated FIT group: 8.3% mortality within 1 year.
• Lower FIT group: 2.8% mortality within 1 year.
• This represents a **nearly threefold increase** in 1-year mortality in the elevated FIT group compared to the lower FIT group.
• **All-cause mortality rate:**
• Elevated FIT group: 87.21 deaths per 1000 person-years.
• Lower FIT group: 28.41 deaths per 1000 person-years.

• **Non-CRC mortality:**
• Elevated FIT group: 92.4% of all deaths in this group were non-CRC related.
• Non-CRC mortality rate: 74.79 per 1000 person-years in the elevated FIT group vs 27.72 per 1000 person-years in the lower FIT group.

• **CRC-specific mortality:** While mortality due to CRC increased with higher FIT levels, the majority of excess deaths in the elevated FIT group were attributed to **non-CRC causes**.

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### 2. **Adjusted Risk of Mortality (High FIT vs Low FIT):**

• After adjusting for factors such as age, sex, and year, patients with elevated FIT results (≥ 10 µg Hb/g) had:
• **Nearly double the risk of all-cause mortality** (adjusted hazard ratio [aHR]: 1.96).
• **1.7 times higher risk of non-CRC mortality** (aHR: 1.70).
• These findings indicate that high FIT results are predictive of a systemic vulnerability to death beyond CRC alone.

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### 3. **Standardized Mortality Ratios (SMRs):**

• For patients with FIT ≥ 10 µg Hb/g:
• SMR for **all-cause mortality**: 2.12 (indicating a more than twofold excess risk compared to the general population).
• SMR for **non-CRC mortality**: 1.86 (indicating significantly higher risk of non-CRC-related deaths).

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### 4. **Demographic and Subgroup Insights:**

• **Age:** Younger symptomatic patients with elevated FIT results showed particularly pronounced relative increases in mortality risk, highlighting that high FIT is worrisome even in traditionally lower-risk age groups.
• **Sex differences:** Women with elevated FIT results demonstrated a greater relative risk of mortality compared to men, suggesting potential biological or diagnostic differences.

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### 5. **Possible Mechanisms for Elevated Mortality in High-FIT Patients:**

• Elevated FIT results may signal underlying systemic health issues beyond CRC, such as:
• **Cardiovascular disease.**
• **Other malignancies.**
• **Inflammatory conditions** or other comorbidities.
• These conditions may contribute to the significantly higher non-CRC mortality observed in the elevated FIT group.

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### 6. **Clinical and Public Health Implications:**

• **Red flag for overall mortality risk:** A positive FIT result in symptomatic patients should not be viewed solely as a marker of CRC risk but as an indicator of **increased overall mortality risk**.
• **Comprehensive evaluation required:** High-FIT patients should undergo urgent diagnostic workup and closer surveillance for both CRC and non-CRC conditions.
• **Prognostic utility:** FIT may serve as a biomarker of systemic disease burden, providing prognostic insights beyond its traditional role in CRC detection.

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### 7. **Limitations of the Study:**

• The study was retrospective and conducted within a single regional healthcare system (Nottingham University Hospitals), which may limit generalizability to other populations. However, the large cohort size (49,889 adults) strengthens the robustness of the findings.

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### Summary:

High FIT results (≥ 10 µg Hb/g) in CRC patients are associated with significantly worse 1-year mortality outcomes, driven by both CRC-specific and non-CRC-related causes. The findings underscore the importance of interpreting elevated FIT results as a **broad clinical red flag** requiring comprehensive evaluation and management, not only for CRC but also for other underlying health risks.