ORIGINAL PAPERS

 

Long-term oncologic results in cancer of the rectum treated by preoperative chemoradiotherapy and surgery: An analysis of 500 cases

Resultados oncológicos a largo plazo en el cáncer de recto tratado con quimio-radioterapia preoperatoria y cirugía: análisis de 500 casos

 

 

Javier A.-Cienfuegos¹, Jorge Baixauli¹, Carlos Pastor², Jorge Arredondo³, Jesús Javier Sola⁴, Leire Arbea⁵, Ana Chopitea⁵ and José Luis Hernández-Lizoáin¹

¹Department of General Surgery. Clínica Universidad de Navarra. Pamplona, Navarra. Spain.
²Department of General Surgery. Fundación Jiménez Díaz. Madrid, Spain.
³Department of General Surgery. Complejo Hospitalario León. León, Spain.
⁴Department of Pathology. Hospital San Pedro. Logroño, La Rioja. Spain.
⁵Department of Oncology. Clínica Universidad de Navarra. Pamplona, Navarra. Spain

Correspondence

 

 

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ABSTRACT

Background: The standard treatment for locally advanced cancer of the rectum (LACR) and selective cases of stage IV disease is preoperative chemoradiotherapy (CRT) followed by total mesorectal excision (TME). Despite reductions in local recurrence, disease-free survival (DSF) has remained stable in recent years.
Objective: The objective of this study is to analyze patterns of recurrence, long-term survival and prognostic factors in a program of neoadjuvant CRT and surgery in LACR.
Methods: Between January 1992 and December 2011, 446 patients with LACR and 54 patients (with single metastases) were treated with pre-operative long course CRT and surgery. Three hundred forty four (66.8%) anterior resections of the rectum and 123 (24.6%) abdomino-perineal resections were performed.
Results: With a mean follow-up of 70.06 months, local recurrence was 4.8% and distant recurrence 25.5%. No differences were found in the histopathologic prognostic factors across the three groups studied depending on distance (cm) from the anal margin. Involvement of the circumferential resection margin (CRM+) was significantly greater in tumors in the distal third of the rectum (8.5%; p = 0.04). 67 patients (13.4%) showed a complete pathologic response. DSF at 5 and 10 years was significantly lower in patients with tumors affecting the distal third as compared to the middle third of the rectum (61.9% vs. 57.7%; p = 0.04). Tumors at this distal location resulted in a significantly higher incidence of lung metastases (p = 0.016).

Key words: Rectal cancer. Neoadjuvant chemoradiotherapy. Survival. Recurrence pattern. Total mesorectal excision.

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RESUMEN

Antecedentes: el tratamiento del cáncer de recto localmente avanzado (CRLA) y de casos selectivos de estadio IV es la quimio-radioterapia (QRT) preoperatoria seguida de la extirpación completa del meso-recto (ETM). A pesar de la reducción en la recurrencia local, la supervivencia libre de enfermedad (SLE) permanece estable en los últimos años.
Objetivo: el objetivo de este trabajo es analizar el patrón de recidiva, supervivencia a largo plazo y los factores pronósticos en un programa de QRT neoadyuvante y cirugía en el CRLA.
Métodos: ent re enero de 1992 y diciembre de 2011, 446 pacientes con CRLA y 54 pacientes (con metástasis únicas) fueron tratados con QRT preoperatoria de curso largo y cirugía. Se realizaron 344 (68,8%) resecciones anteriores de recto y 123 (24,6%) amputaciones abdominoperineales.
Resultados: con una mediana de seguimiento de 70,06 meses, la recurrencia local fue del 4,8% y a distancia del 25,5%. No se encontraron diferencias en los factores pronósticos histopatológicos entre los tres grupos estudiados dependiendo de la distancia (cm) al margen anal. La afectación del margen circunferencial (MCR+) fue significativamente mayor en el tercio distal (8,5%; p = 0,04). Sesenta y siete pacientes (13,4%) mostraron una respuesta patológica completa. La supervivencia libre de enfermedad a los 5 y 10 años fue significativamente menor en los tumores del tercio distal del recto que en los del tercio medio (61,9% y 57,7%; p = 0,04). En dicha localización se produjo una incidencia significativamente mayor de metástasis pulmonares (p = 0,016).

Palabras clave: Cáncer recto. Quimio-radioterapia preoperatoria. Supervivencia. Patrón de recurrencia. Escisión completa meso-recto.

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Introduction

The standard treatment for locally advanced cancer of the rectum (LACR), stages II (T3-T4 N0) and III (any T, N+ MO) and, in very selective cases, of stage IV (resectable synchronous metastases) is the combination of pre-operative long course chemoradiotherapy (CRT) with total mesorectal excision (TME) (1-3). Although a reduction in local recurrence (≈40%) and an increase in the preservation of sphincters have been achieved, overall survival (OS) and disease-free survival (DFS) have remained stable over the last ten years (4). Curiously, unlike what has happened with local recurrence (5,6), few studies have analyzed patterns of long-term systemic recurrence. In spite of the advances in imaging techniques [nuclear magnetic resonance (NMR), molecular imaging] and tumor biomarkers, the most important prognostic factors are histopathologic findings (yTNM, degree of pathologic response, perineural and lymphovascular infiltration and invasion of the circumferential resection margin - CRM) following protectomy (7-11). In order to improve results and select the most effective treatment, it is essential to determine patterns of recurrence and their relationship with the prognostic factors listed above.

In this study we analyze the oncological results and patterns of local and systemic recurrence and their relationship with clinical pathologic factors in a series of 500 patients treated consecutively with long course neoadjuvant CRT and surgery with TME.

 

Materials and methods

Patients

We performed a retrospective study on 500 patients with cancer of the rectum, 446 with locally advanced cancer (LARC) (stages II-III, cT3-4 or N+, American Joint Commission Cancer [AJCC]^*) (12), and 54 patients with stage IV disease, treated consecutively with pre-operative CRT and surgery based on TME in the Clínica Universidad de Navarra (Spain) between 1992 and 2011. Patients were identified from a prospective institutional database and the study was approved by the local Research Ethics Committee. Patients with multiple synchronous or unresectable metastases (advanced stage IV disease), concurrent inflammatory disease, hereditary colon cancer syndromes, a previous history of malignancy or concurrent tumors and those undergoing emergency surgery were excluded from the study.

Clinical staging, treatment and pathologic assessment

Clinical staging (cTNM) was carried out using CT scans of the thoracic, abdominal and pelvic regions, NMR imaging and endoscopic ultrasound from 1998. Two different neoadjuvant chemotherapeutic regimens were employed; 5-fluorouracil (5-FU) (225 mg/m²/day on days 1-4 and 24-28) alone, or capecitabine (825 mg/m²/day from Monday to Friday) in combination with oxaliplatin (60 mg/m² i.v. on days 1, 8 and 15). At the same time patients received external radiotherapy (1.8 Gy/day, five days a week over five weeks, for a total dose of 45 Gy) in 3 or 4 fields, or intensity-modulated radiation therapy in 7 fields as described previously (13).

In 80 patients (16%) with cT4 and or N+ tumors of the middle or distal third of the rectum, fixed tumors or those occupying ≥ 50% of the rectal lumen, an overdose/superimposition was administered using intraoperative radiotherapy (IOR) (12.5 cGy) once those areas at greatest risk for local and regional recurrence (the presacral area, the tumoral bed) had been excised using a technique we have described previously (14).

Patients underwent surgery 4-6 weeks after completing the neoadjuvant treatment. In all operations involving the middle or lower third of the rectum, total mesorectal excision, anterior excision of the rectum (AR), abdominoperineal resection (APR) and Hartmann's procedure were performed.

In tumors of the upper third (10 cm above the anal margin), selective resection of at least the 5 cm distal to the tumor of the mesorectum was performed. In tumors affecting the distal third, the decision to perform an ultralow anterior resection with a mechanical or manual coloanal anastomosis depended on the surgeon responsible as did the choice of creating a temporary ileostomy and/or a J-pouch reservoir (15).

In some patients with a good response to the CRT in the endoscopy, rectal examination or NMR, those with tumors at clinical stage T1, < 3 cm in diameter, occupying less than 1/3 of the endoluminal circumference and with no lymphovascular or perineural infiltration, local resection was performed using transanal endoscopic microsurgery (TEM) (15). Half of the patients (n = 247, 49.5%) received neoadjuvant chemotherapy for 6 months and 15 patients (3%) received radiotherapy alone with no neoadjuvant chemotherapy.

Follow-up

Local recurrence was defined as clinical, pathologic and/or radiologic confirmation of malignant disease in the field of irradiation. Systemic recurrence was defined as clinical, radiologic and/or pathologic confirmation of reappearance of the tumor at a different anatomic site. Recurrence was confirmed using 2 CT scans with an interval of 4-6 weeks between each.

Pathologic analysis

Pathologic analysis was carried out by a pathologist (JJS) who is an expert in gastrointestinal tumors. Involvement of the circumferential resection margin was defined as the presence of a tumor ≤ 1 mm from the margin (16-17).

Tumors were staged -yTNM- following the AJCC classification (7^th edition, 2010) and the degree of perineural and lymphovascular invasion was determined and the lymph node index (the quotient of the affected nodes and the total number of nodes) calculated (12,16,17).

The histological response of the tumor to the chemoradiotherapy was reviewed specifically for this study by JJS and JLHL following the criteria of Shia et al. (8). Accordingly, 6 degrees of response were established: grade 0, grade 1 (≤ 33% response), grade 2 (> 33% and ≤ 66% response), grade 3 (> 67% and ≤ 94% response), grade 3+ (> 95% and ≤ 99% response, almost complete, < 1% foci or microscopic trace) and grade 4 (complete response -pCR- 100% or absence of tumor).

Statistical analysis

Data were analyzed using the statistical program Statistical Package for Social Sciences (SPSS Inc., Chicago, IL. V15.0 for Windows). Quantitative variables were expressed as means or medians depending on whether their distribution was normal or not. Categorical variables were expressed using absolute frequencies and percentages.

For comparison of proportions (frequencies) of qualitative variables between groups, contingency methods [chi-squared tests (χ²)] were used.

Survival analyses

Accumulated survival was calculated using Kaplan-Meier curves and the groups were compared using the nonparametric Mantel-Cox (log-rank) test. Survival, incidence of local recurrence and distant metastases were compared across the three groups depending on the distance of the tumor from the anal margin: The upper third (> 10 cm), the middle third (> 5 cm and < 10 cm) and the distal third (≤ 5 cm) of the rectum.

 

Results

Overall characteristics of the series

The clinical, therapeutic and pathologic characteristics of the series are shown in tables I and II. Patients' mean age was 58.9 years (range 24-87), 339 patients (67.8) were male and 161 (32.2%) female. All patients completed treatment with radiotherapy with a mean duration of 34.9 days and a mean dose of 49.9 Gy. Most patients (68.8%) underwent anterior resection of the rectum and abdominoperineal resection was performed in 123 (24.6%). In 13 patients (2.6%) local resection of the tumor (TEM) was performed. In 209 patients (41.8%) coloanal anastomoses were created, of which 23 involved a J-pouch reservoir (Table I).

 

 

Mean hospital stay was 11.3 days with no significant differences across the three groups (Tables I and II). Operative mortality in the complete series was 0.06% (3 patients).

Of the 54 patients (10.8%) with synchronous metastases, 35 had liver metastases, in 12 peritoneal carcinomatosis was found during surgery and 7 had lung metastases.

The mean distance of the tumor from the anal margin was 6.5 cm. In 164 patients (32.8%) there was involvement of the lymph nodes, of which 121 (24.2%) were N1 (metastases in 1-3 regional lymph nodes) and 43 (8.6%) were N2 (metastases in 4 or more regional lymph nodes).

The mean number of dissected lymph nodes was 10.7 and that of lymph nodes affected 1.04, with a lymph node index of 0.328. In the majority of patients (n = 331; 66.2%) more than 12 lymph nodes were dissected.

The degree of tumor response to the chemoradiotherapy was simplified into 4 categories by conflating categories 1 and 2. Ninety-three patients (18.6%) showed a near-complete response and 30 (12%) showed a complete response (pCR). In 103 patients (20.6%) perineural invasion was observed and in 97 (19.4%) lymphovascular invasion was found.

Table II shows the clinical characteristics and the type of surgery performed according to tumor site. In 171 patients (89.5%) with lesions in the middle third it was possible to perform low rectal anterior resection as it was in 45% of tumors in the distal third. There were no significant differences in operative mortality or length of hospital stay although operative time in patients undergoing APP was longer. The 6 pathologic prognostic factors analyzed -TNM, lymphovascular and perineural invasion, lymph node index, degree of tumor response and distal margin- were similar across the three groups.

However, we observed a higher incidence (p = 0.047) of CRM involvement in tumors of the distal third (8.5%) as compared to those of the upper (3%) and the middle thirds (2.6%) (Table II).

Survival analyses

Median follow-up was 70.06 months for OS and 56 months for DSF and overall and disease-free survival at 5 and 10 years were 76.9% and 66% and 69% and 64.6% respectively.

Tumor recurrence occurred in 125 of 446 patients (28%) with 24 (5.3%) developing local recurrences and 114 (25.6%) distant recurrences. Distant recurrences involved the lungs in 89 patients (19.9%) and the liver in 45 patients (10.1%). We observed a significantly higher incidence of lung recurrences in tumors of the distal third of the rectum [n = 55 (25.5%); p = 0.016] (Table III).

 

 

DSF at 5 and 10 years as related to yTNM staging (AJCC) is shown in figure 1. With similar follow-up, patients with distal tumors had a significantly worse DFS at 5 and 10 years than those with middle third tumors: 61.9% and 57.7% (p = 0.048) (Fig. 2).

 

 

Discussion

The standard treatment for locally advanced cancer of the rectum stages II (T3-4 N0) and III (any T N+ M0) and some at stage IV (synchronous metastases) is neoadjuvant chemoradiotherapy and total mesorectal excision (1-3,18).

Following this guideline, in stages II and III a significant reduction in local recurrence (40%) and an increase in the preservation of sphincters has been reported although disease-free survival has remained stable over the last 10 years. For this reason some groups have initiated phase II trials in which systemic chemotherapy has been prioritized and intensified. Some trials currently under way even avoid preoperative radiotherapy and its adverse effects (19).

In spite of the advances in preoperative staging, the most important prognostic factors continue to be the histologic criteria following protectomy. The aim of this study was to analyze survival and patterns of recurrence in 500 patients with cancer of the rectum that were treated in the same center with preoperative CRT and surgery with TME with a mean follow-up of 70.06 months.

The clinical characteristics of the series and the type of surgery performed are very similar to those reported by other groups (20). In 54 patients (10.8%) distant disease was present at the time of surgery, a figure similar to that reported by other authors (21). In 68.85% of all patients and in 45% of tumors of the distal third it was possible to perform resection with preservation of sphincters. The overall incidence of APP was 24.6% with an operative mortality of 0.6%, a figure similar to that reported by reference centers and clinical guidelines.

An incidence of circumferential margin involvement of 5.7% and a median of 10.7 lymph nodes dissected in the specimen are in line with data reported by authors with proven experience with TME. The same is true of other histopathologic parameters (degree of venous and lymphovascular invasion). The categories of the degree of histologic response to the preoperative treatment (Table II) are similar to those reported by Shia et al. (8).

Most authors, including ourselves, have found a correlation between degree of pathologic response and survival (8,9,11). Such findings, together with the experience reported by Habr-Gama and advances in NMR have led to clinical trials focusing on a "wait and see" approach (22).

Overall local recurrence in our series was 5.3%, a figure in line with that reported by other authors specialized in colorectal surgery but lower than that reported in most series. We found no difference in local recurrence across the three groups depending on the distance of the tumor from the anal margin. In contrast, patients with tumors in the lower third had a worse disease-free survival at 5 and 10 years (Fig. 2) as a result of the development of lung metastases. Such findings contrast with those reported by several authors but are in agreement with more recent series that have investigated this issue (20). Some studies have associated this biological behavior with transgression of the oncological surgical criteria inherent in the surgical technique of APP, known as the "waist" or "coning" effect as a result of the absence of the fat of the mesorectum in the distal third of the rectum (3,21,24).

Our 8.5% incidence of CRM in tumors of the distal third is similar to that reported in single series focusing on this issue and lower than those published in multicenter studies which have reported figures of between 15% and 25% for CRM involvement (25-27).

The greater incidence of systemic recurrences has been associated with venous drainage of the anorectum by the hemorrhoidal veins medial and lower to the internal iliac veins and to systemic circulation (23). Other authors have linked this to the mechanisms of resistance of lung metastases to 5-FU, as the increase in the expression of thymidylate synthase in tissue reduces the efficacy of fluoropyrimidines (28). In contrast, other authors have reported that neoadjuvant CRT disrupts tumor biology, limiting the development of liver metastases in favour of lung metastases (29). Finally, the preponderance of lung metastases could be due, according to Ding (23), to the intense monitoring with imaging techniques as they are normally detected with a CT scan with diameters of less than 1 cm when they are not accessible by fine-needle aspiration biopsy with the resulting increase in the time interval between detection and confirmation.

The findings that the lungs most frequently are the site of systemic recurrence in LACR is supported by current follow-up guidelines for colorectal cancer which recommend a yearly thoracic and abdominal CT scan for the first 5 years (1).

Our results, as do those of other authors, suggest that it is advisable to treat LACR early as a systemic disease, especially when tumors are found in the distal third of the rectum.

Our study suffers from the limitations inherent in retrospective studies covering a large period of time (20 years) such as the introduction of new drugs and modulated-intensity radiotherapy during this time. However, it has the advantage of being a large homogeneous series -500 patients- undergoing long-term follow-up by the same multidisciplinary team.

Furthermore, the guidelines for chemotherapy and radiotherapy for cancer of the rectum have not varied a great deal in recent years as targeted therapies have not shown the expected benefit and have even led to an increase in adverse effects. As we have described, there is a tendency for current strategies to change the sequence of those techniques complementary to surgery and to individualize surgery depending on the "degree of response" to CRT.

In conclusion, our results demonstrate that disease-free survival for tumors of the distal third of the rectum is shorter given the greater risk of patients developing lung metastases.

 

Acknowledgements

The authors thank Mrs. Lydia Munarriz for manuscript editing and acknowledge to Paul Miller Ph.D. for English version.

 

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Correspondence:
Javier A.-Cienfuegos.
Department of General Surgery.
Clínica Universidad de Navarra.
Av. Pío XII, 36.
31008 Pamplona, Navarra.
Spain
e-mail: fjacien@unav.es

Received: 20-01-2015
Accepted: 05-03-2015