The role of circulating tumor cells and K-ras mutations in patients with locally advanced rectal cancer: a prospective study

Case Report: Long-term survival of a patient with advanced rectal cancer and multiple pelvic recurrences after seven surgeries

Background

Rectal cancer has a high risk of recurrence and metastasis, with median survival ranging from 24 months to 36 months. K-RAS mutation is a predictor of poor prognosis in rectal cancer. Advanced rectal cancer can be stopped in its tracks by pelvic exenteration.

Case summary

A 51-year-old woman was diagnosed with advanced rectal cancer (pT4bN2aM1b, stage IV) with the KRAS G12D mutation due to a change in bowel habits. The patient had experienced repeated recurrences of rectal cancer after initial radical resection, and the tumor had invaded the ovaries, sacrum, bladder, vagina and anus. Since the onset of the disease, the patient had undergone a total of seven surgeries and long-term FOLFIRI- or XELOX-based chemotherapy regimens, with the targeted agents bevacizumab and regorafenib. Fortunately, the patient was able to achieve intraoperative R0 resection in almost all surgical procedures and achieve tumor-free survival after pelvic exenteration. The patient has been alive for 86 months since her diagnosis.

Conclusions

Patients with advanced rectal cancer can achieve long-term survival through active multidisciplinary management and R0 surgery.

Planning adaptive treatment by longitudinal response assessment implementing MR imaging, liquid biopsy and analysis of microenvironment during neoadjuvant treatment of rectal cancer (PRIMO)

INTRODUCTION

Conducting neoadjuvant chemoradiotherapy (CRT) and additional preoperative consolidating chemotherapy (CTx), that is, total neoadjuvant therapy (TNT), improves local control and complete response (CR) rates in locally advanced rectal cancer (LARC), putting the focus on organ preservation concepts. Therefore, assessing response before surgery is crucial. Some LARC patients would either not benefit from intensification by TNT or may reach CR, making resection not mandatory. Treatment of LARC should therefore be based on patient individual risk and response to avoid overtreatment.The "PRIMO" pilot study aims to determine early response assessment to form a basis for development and validation of a noninvasive response prediction model by a subsequent prospective multicenter trial, which is highly needed for individual, response-driven therapy adaptions.

METHODS

PRIMO is a prospective observational cohort study including adult patients with LARC receiving neoadjuvant CRT. At least 4 multiparametric magnetic resonance imaging (MRI) scans (diffusion-weighted imaging [DWI] and hypoxia-sensitive sequences) as well as repeated blood samples in order to analyze circulating tumor cells (CTC) and cell-free tumor DNA (ctDNA) are scheduled. Pelvic radiotherapy (RT, 50.4 Gy) will be performed in combination with a 5-fluorouracil/oxaliplatin regimen in all patients (planned: N = 50), succeeded by consolidation CTx (FOLFOX4) if feasible. Additional (immuno)histochemical markers, such as tumor-infiltrating lymphocytes (TIL) and programmed death ligand 1 (PD-L1) status will be analyzed before and after CRT. Routine resection is scheduled subsequently, nonoperative management is offered alternatively in case of clinical CR (cCR).The primary endpoint is pathological response; secondary endpoints comprise longitudinal changes in MRI as well as in CTCs and TIL. These are evaluated for early response prediction during neoadjuvant therapy, in order to develop a noninvasive response prediction model for subsequent analyses.

DISCUSSION

Early response assessment is the key in differentiating "good" and "bad" responders during neoadjuvant CRT, allowing adaption of subsequent therapies (additional consolidating CTx, organ preservation). This study will contribute in this regard, by advancing MR imaging and substantiating new surrogate markers. Adaptive treatment strategies might build on these results in further studies.

Prognostic and Predictive Biomarkers in Patients with Locally Advanced Rectal Cancer (LARC) Treated with Preoperative Chemoradiotherapy

Neoadjuvant chemoradiotherapy (CRT) is one of the standards of care in locally advanced rectal cancer (LARC). This retrospective study examines clinical, analytical, and pathological parameters collected from 77 patients with locally advanced (cT3-4 or cN+) rectal carcinoma diagnosed between 2007 and 2017 at our institution that were treated with preoperative CRT and surgery. In the prognosis analysis, lower hemoglobin levels (p = 0.008), lower lymphocyte/monocyte ratio (LMR) (p = 0.011), and higher platelet/lymphocyte ratio (PLR) (p = 0.029) in the second determination (Hb2, LMR2 and PLR2) were associated with the relapse group. The number of positive nodes after surgery (N+) showed a statistically significant association with relapse (p = 0.012). KRAS mutations were associated with a worse prognosis for 5 years progression-free and overall survival (p = 0.005 and 0.022; respectively). We propose a prognostic model based on four parameters (number of positive lymph nodes after surgery, hemoglobin levels, LMR, and PLR after neoadjuvant therapy) that can be a useful tool to estimate relapse risk. Moreover, bilirubin could be a useful parameter to predict the response to neoadjuvant CRT.

Biomarkers in Locally Advanced Rectal Cancer: A Review

Locally advanced rectal cancers (LARC) are the subject of a rapidly evolving treatment paradigm. The critical timepoints where management decisions are required during the care of the LARC patient are: prior to the institution of any treatment, post neoadjuvant therapy and post-surgery. This article reviews the clinical, imaging, blood-based, tissue-based, and molecular biomarkers that can assist clinicians at these timepoints in the patient's management, in prognosticating for their LARC patients or in predicting responses to therapy in the multi-modality neoadjuvant treatment era.

KRAS mutation is predictive for poor prognosis in rectal cancer patients with neoadjuvant chemoradiotherapy: a systemic review and meta-analysis

PURPOSE

To investigate the association between KRAS mutation and prognosis in rectal cancer patients with neoadjuvant chemoradiotherapy.

METHODS

Literature was searched in the databases including Cochrane Library, EMBASE (Ovid), and MEDLINE (PubMed) from inception to December 16, 2020. The keywords "rectal cancer" or "rectal carcinoma" or "rectal adenocarcinoma" and "KRAS" and "neoadjuvant" were used for preliminary literature retrieval. Pooled odds ratios (ORs) and 95% confidence intervals (95%CIs) were calculated for the KRAS mutation and clinical outcomes including overall survival (OS), disease-free survival (DFS), pathologic complete remission (pCR), downstaging of T stages and tumor stages, as well as improvements in tumor regression grading (TRG). Publication bias was assessed by the funnel plots.

RESULTS

A total of 16 articles were included for eligibility. The total number of patients was 3674 cases, with an incidence of KRAS gene mutation of 36.6% (1346/3674). Meta-analysis showed that the pooled OR for KRAS mutation on OS was 1.33 (95%CI: 113-1.56). Consistently, results also indicated that the KRAS mutant was related to the poor DFS (pooled OR=1.55, 95%CI: 1.19-2.02). However, KRAS mutation is not related to the PCR (pooled OR= 0.71, 95%CI: 0.44-1.14), downstaging in T stages (pooled OR= 0.66, 95%CI: 0.42-1.06), tumor stages (pooled OR= 1.18, 95%CI: 0.78-1.78, I2=12.9%), as well as improvement in TRG grades (pooled OR= 0.84, 95%CI: 0.59-1.20).

CONCLUSION

KRAS mutation is a predictor for the poor prognosis of neoadjuvant chemoradiotherapy in patients with rectal cancer, but it is not related to the responses of tumors after treatment.