Loss of skeletal muscle index and survival in patients with metastatic colorectal cancer: Secondary analysis of the phase 3 CAIRO3 trial

Background

Low skeletal muscle index (SMI) in metastatic colorectal cancer (mCRC) patients is associated with poor outcomes. The prognostic impact of SMI changes during consecutive palliative systemic treatments is unknown.

Methods

This is a retrospective analysis of the phase 3 CAIRO3 study. The CAIRO3 study randomized 557 patients between maintenance capecitabine + bevacizumab (CAP‐B) or observation, after six cycles capecitabine + oxaliplatin + bevacizumab (CAPOX‐B). Upon first disease progression (PD1), CAPOX‐B was reintroduced until second progression (PD2). SMI was assessed by computed tomography (CT) (total 1355 scans). SMI and body mass index (BMI) changes were analyzed for three time‐periods; p1: during initial CAPOX‐B, p2: randomization to PD1, and p3: PD1 to PD2. The association between absolute and change in SMI and BMI (both per 1 standard deviation) during p1‐p3, with PD1, PD2, and survival was studied by Cox regression models.

Results

This analysis included 450 of the 557 patients randomized in the CAIRO3 study. Mean SMI decreased during p1: mean −0.6 SMI units [95% CI −1.07;‐0.26] and p3: −2.2 units [−2.7;‐1.8], whereas during p2, SMI increased + 1.2 units [0.8‐1.6]. BMI changes did not reflect changes in SMI. SMI loss during p2 and p3 was significantly associated with shorter survival (HR 1.19 [1.09‐1.35]; 1.54 [1.31‐1.79], respectively). Sarcopenia at PD1 was significantly associated with early PD2 (HR 1.40 [1.10‐1.70]). BMI loss independent of SMI loss was only associated with shorter overall survival during p3 (HR 1.35 [1.14‐1.63]).

Conclusions

In mCRC patients, SMI loss during palliative systemic treatment was related with early disease progression and reduced survival. BMI did not reflect changes in SMI and could not identify patients at risk of poor outcome during early treatment lines.

Skeletal muscle mass loss and dose-limiting toxicities in metastatic colorectal cancer patients

BACKGROUND

Increasing evidence suggests that severe skeletal muscle index (SMI) loss (sarcopenia) is associated with poor overall survival in metastatic colorectal cancer patients, but its mechanisms are unknown. We recently found, using data of the randomized phase 3 CAIRO3 study, that SMI loss was related with shorter time to disease progression and overall survival during first-line maintenance treatment with capecitabine + bevacizumab (CAP-B) or observation and during more intensive capecitabine + oxaliplatin + bevacizumab (CAPOX-B) reintroduction treatment. As a potential risk factor for reduced survival, we explored whether sarcopenia and SMI loss were associated with dose-limiting toxicities (DLTs) during CAP-B and CAPOX-B.

METHODS

Sarcopenia status and SMI loss were assessed by using consecutive computed tomography scans. DLTs were defined as any dose delay/reduction/discontinuation of systemic treatment because of reported CTCAE (version 3.0) toxicities at the start or during treatment. Poisson regression models were used to study whether sarcopenia and body mass index (BMI) at the start of treatment and SMI and BMI loss during treatment were associated with DLTs.

RESULTS

One hundred eighty-two patients (mean age 63.0 ± 8.8 years, 37% female) received CAP-B, and 232 patients (mean age 63.0 ± 9.0 years, 34% female) received CAPOX-B. At the start of CAP-B and CAPOX-B, 54% and 46% of patients were sarcopenic, respectively. Mean BMI was lower in sarcopenic patients, although patients were on average still overweight (sarcopenic vs. non-sarcopenic at the start of CAP-B 25.0 ± 3.9 vs. 26.7 ± 4.1 and CAPOX-B 25.8 ± 3.8 vs. 27.1 ± 3.8 kg/m² ). Sarcopenia at the start of CAP-B was not associated with DLTs [relative risk 0.87 (95% confidence interval 0.64-1.19)], whereas patients with >2% SMI loss had a significantly higher risk of DLTs [1.29 (1.01-1.66)]. At the start of subsequent CAPOX-B, 25% of patients received a dose reduction, and the risk of dose reduction was significantly higher for patients with preceding SMI loss [1.78 (1.06-3.01)] or sarcopenia [1.75 (1.08-2.86)]. After the received dose reductions, sarcopenia or SMI loss was not significantly associated with a higher risk of DLTs during CAPOX-B [sarcopenia vs. non-sarcopenic: 0.86 (0.69-1.08) and SMI loss vs. stable/gain: 0.83 (0.65-1.07)]. In contrast, BMI (loss) at the start or during either treatment was not associated with an increased risk of DLTs.

CONCLUSIONS

In this large longitudinal study in metastatic colorectal cancer patients during palliative systemic treatment, sarcopenia and/or muscle loss was associated with an increased risk of DLTs. BMI was not associated with DLTs and could not detect sarcopenia or SMI loss. Prospective (randomized) studies should reveal whether normalizing chemotherapeutic doses to muscle mass or muscle mass preservation (by exercise and nutritional interventions) increases chemotherapeutic tolerance and improves survival.

Impact of skeletal muscle index (SMI) loss during palliative systemic treatment (Tx) on time to progression and overall survival (OS) in metastatic colorectal cancer (mCRC) patients

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Background: Evidence for a strong link between skeletal muscle depletion and poor outcomes in mCRC is growing. However, the impact of SMI changes over time on progression and OS during palliative systemic Tx is not known. The CAIRO3 study (Simkens et al. Lancet 2015) randomized 556 mCRC patients after 6 cycles capecitabine+oxaliplatin+bevacizumab (CAPOX-B) to maintenance CAP-B Tx (Main) vs. observation (Obs). Upon 1st disease progression (PD1), CAPOX-B or other treatment was reintroduced until 2nddisease progression (PD2). This is the first analysis using scan data of multiple time-points to investigate SMI changes during palliative systemic treatment Tx and its association with survival. Methods: 1227 CT-scans of a random selection of 416 CAIRO3 patients (mean age 64±9 years, Main n = 206; Obs n = 210) were analyzed for SMI (skeletal muscle area at the L3 level in cm2/m2). Using mixed model analysis, SMI changes were analyzed for two intervals; interval 1: from randomization to PD1, and interval 2: from PD1 to PD2. Three Cox regression models were used to study the association between SMI loss and time to PD2 and death for interval 1, and time to death for interval 2. Main and Obs groups were combined in the analyses since the p-value for interaction was not significant. Hazard ratios (HR) were reported per 2 units change in SMI. Results: Median times from randomization to PD1, PD2 and death were 7.7, 13.5 and 24 months resp. During interval 1 (less intensive or no Tx) patients gained SMI on average (1.2 units; 95%CI 0.6-1.8), but 23% of patients still lost SMI. SMI loss was associated with shorter time to PD2 (HR 0.88; 0.81-0.98, p= .01), but not with shorter OS (HR 0.94; 0.86-1.02, p= .17). During interval 2 (more intensive Tx) average SMI loss was -2.2 units ( 1.5-2.8) and 63% of patients lost SMI. SMI loss was associated with shorter OS (HR 0.73; 0.62-0.86, p< .00). Conclusions: Loss of SMI was related to shorter time to progression during first line less intensive main Tx or obs and shorter overall survival during more intensive reinduction Tx. This large longitudinal study suggests that SMI preservation may be a therapeutic goal. Clinical trial information: NCT00442637.