The American Journal of Surgery (2014) 207, 493-498

Clinical Science

Tumor growth pattern as predictor of colorectal livermetastasis recurrence

Rafael S. Pinheiro, M.D.a,*, Paulo Herman, M.D.a, Renato M. Lupinacci, M.D.a,Quirino Lai, M.D.b, Evandro S. Mello, M.D.c, Fabricio F. Coelho, M.D.a,Marcos V. Perini, M.D.a, Vincenzo Pugliese, M.D.a, Wellington Andraus, M.D.a,Ivan Cecconello, M.D.a, Luiz Carneiro D’Albuquerque, M.D.a

aDepartment of Gastroenterology, University of Sao Paulo M�

edical School, Hospital das Clınicas, Rua Dr Eneas deCarvalho Aguiar, 255, 9 Andar-sala 9113/9114, CEP 05403-900, Sao Paulo, Brazil; bDepartment of General Surgery andOrgan Transplantation, Sapienza University of Rome, Umberto I Policlinic of Rome, Rome, Italy; cDepartment ofPathology, University of Sao Paulo Medical School, Sao Paulo, Brazil

KEYWORDS:Colorectal neoplasms;Colorectal metastasis;Hepatectomy;Pathology;surgical;Recurrence

The authors declare no conflict of in

* Corresponding author. Tel.: 155-1

6250.

E-mail address: rsnpinheiro@gmail.c

Manuscript received March 10, 2013

2013

0002-9610/$ - see front matter � 2014

http://dx.doi.org/10.1016/j.amjsurg.20

AbstractBACKGROUND: Surgical resection is the gold standard therapy for the treatment of colorectal liver

metastases (CRM). The aim of this study was to investigate the impact of tumor growth patterns ondisease recurrence.

METHODS: We enrolled 91 patients who underwent CRM resection. Pathological specimens wereprospectively evaluated, with particular attention given to tumor growth patterns (infiltrative vs push-ing).

RESULTS: Tumor recurrence was observed in 65 patients (71.4%). According to multivariate anal-ysis, 3 or more lesions (P 5 .05) and the infiltrative tumor margin type (P 5 .05) were unique indepen-dent risk factors for recurrence. Patients with infiltrative margins had a 5-year disease-free survival ratesignificantly inferior to patients with pushing margins (20.2% vs 40.5%, P 5 .05).

CONCLUSIONS: CRM patients with pushing margins presented superior disease-free survival ratescompared with patients with infiltrative margins. Thus, the adoption of the margin pattern can representa tool for improved selection of patients for adjuvant treatment.� 2014 Elsevier Inc. All rights reserved.

Colorectal cancer (CRC) is the fourth leading cause ofcancer-related death among men and the fifth amongwomen.1,2 About 60% of patients with CRC treated with cur-ative intent will present with metastatic disease3; in most

terest.

1-2661-3323; fax: 155-11-2661-

om

; revised manuscript May 13,

Elsevier Inc. All rights reserved.

13.05.015

cases, it is confined to the liver.4 Several studies have shownthat the resection of colorectal liver metastases (CRM) canlead to 5-year survival rates of 25% to 58%.5,6

Many reports have shown a strong correlation betweensurgical margins greater than 1 cm and disease-free long-term survival. Among them, surgical margin evaluation hasbecome a controversial issue. Many reports have shown astrong correlation with surgical margins larger than 1 cm anddisease-free long-term survival. However, in recent years,the aggressive surgical approach in patients with multipleand bilobar nodules has made the 1-cm target margin hard to

494 The American Journal of Surgery, Vol 207, No 4, April 2014

achieve because of insufficient remnant liver parenchyma orthe proximity of the tumor from vascular structures.7–9 In re-cent years, studies addressing surgical margins showed thatpatients submitted to CRM resection with subcentimetricmargins or R1 resections had excellent outcomes.10

In patients with CRC, the tumor growth pattern has beenstudied as an indirect tumor behavior factor predicting tumorrecurrence.11 Disease recurrence was strongly associatedwith infiltrative margins when compared with patients withpushing margins.12–14 The adoption of this classificationhad been used mainly for primary CRC, and there are onlya few studies evaluating metastatic liver disease growth pat-tern showing similar results.15,16 The aim of the presentstudy was to evaluate the impact of the tumor growth patternon local recurrence and survival in patients with metastaticCRC submitted to liver resection.

Patients and Methods

From January 2000 to December 2009, 117 patientsunderwent hepatic resection for CRM. Patients with incom-plete macroscopic resection (R2, n 5 2), preoperativelydetected metastatic extrahepatic disease (n 5 7), earlypostoperative death (within 90 days, n 5 2), and thosewith unavailable specimens for histological assessment (n515) were excluded.

Patient data were obtained from a prospectively col-lected database. Variables analyzed were sex, age, syn-chronous (up to 1 year) or metachronous disease, TNMstaging, pre- and postoperative serum carcinoembryonicantigen, neoadjuvant chemotherapy, number of nodules,size of the largest nodule, presence of uni- or bilateral liverdisease, type of liver resection, tumor differentiation grade,surgical margin status, tumor margin growth pattern (push-ing or infiltrative), presence and time of recurrence, and siteof recurrence.

All specimens were re-evaluated by a senior pathologist.Margins were considered microscopically affected (R1)when the tumor was in contact with the surgical margin; a

Figure 1 A microscopic view of CRM with typical growth pattern repsurrounding hepatic tissue. (B) Infiltrative type: the tumor freely expan

margin of 1 mm or less was considered coincidental butcancer free (R0). The standard growth pattern classificationfor colorectal cancer as proposed by Jass et al11 was adoptedto categorize hepatic metastases. It stratified metastaticgrowth pattern in ‘‘infiltrative’’, when the tumor spreadfreely through the surrounding tissue, dissecting betweennormal hepatocytes in an effortless fashion, usually unop-posed by any form of inflammatory host response. Or‘‘pushing’’, when the tumor’s edges expanded, pushingthe adjacent liver tissue reasonably well circumscribed orinvolved by a thin capsule (Fig. 1). Uncommonly, it is pos-sible to observe dubious areas to precisely define the growthpattern as infiltrative or pushing. In these cases, the overallfindings were used as major criteria to easily stratify it.

Statistical analysis

Univariate logistic regression analysis was performed toevaluate the risk factors for recurrence. Variables withpotential biological or clinical relevance were analyzed.Multivariate logistic regression was performed with vari-ables that had a P value less than .20 according to univariateanalysis. The goodness of fit in each model was analyzedwith the Hosmer-Lemeshow test. Risk prediction wasreported in terms of P values, odds ratios (ORs), and 95%confidence intervals (CIs). A P value less than or equal to.05 indicated statistical significance. The Kaplan-Meiermethod was adopted to evaluate recurrence rates, and thelog-rank test was used for comparison between groups.

Results

Fifty men and 41 women with a mean age of 59 years(range 28 to 81 years) were evaluated. The study populationcharacteristics are reported in Table 1. In 43 cases (47.2%),metastases were synchronous; the remaining patients withmetachronic metastases had a median time of 17 monthsbetween primary tumor resection and the diagnosis of liver

resentations. (A) Pushing type: tumoral edges expand, pushing theds into the normal hepatic tissue.

Table 1 Population characteristics

Variables Pushing Infiltrative Global

Age (y) 54 (28–77) 62 (29–81) 59 (28–81)Male sex (%) 18 (48.6) 32 (59.3) 50 (54.9)MetastasisSynchronous (%) 23 (62.2) 20 (37) 43 (47.2)Metachronous (%) 14 (37.8) 34 (63) 48 (42.8)

Preoperative CEA (ng/dL) 24.75 (1–277) 41.05 (1.4–4,448) 28.5 (1–4,448)Diameter of the biggest lesion (cm) 4 (.5–23.5) 4.5 (1.5–20) 5.2 (.5–23.5)Number of lesions 2.82 (1–10) 2.77 (1–10) 2.9 (1–10).3 lesions (%) 10 (27) 10 (18.5) 20 (22.0)Hepatic resectionAnatomic (%) 27 (73) 31 (57.4) 58 (63.7)Nonanatomic (%) 10 (27) 23 (42.6) 33 (36.3)

R1 surgery (%) 4 (10.8) 7 (13) 11 (12.1)Surgical margin distance,1 mm (%) 13 (35.2) 14 (25.9) 27 (29.6)1–5 mm (%) 11 (29.7) 23 (42.6) 34 (37.4)6–10 mm (%) 4 (10.8) 11 (20.4) 15 (16.5).10 mm (%) 9 (24.3) 6 (11.1) 15 (16.5)

Neoadjuvant chemotherapy 10 (27) 14 (25.9) 24 (26.4)Tumor growth patternPushing (%) 37 (100) d 37 (40.7)Infiltrative (%) d 54 (100) 54 (59.3)

Poor tumor grading (stages III and IV) (%) 2 (5.4) 1 (1.9) 3 (3.3)

CEA 5 carcinoembryonic antigen.

R.S. Pinheiro et al. Tumor growth pattern and CRM 495

metastasis. The mean carcinoembryonic antigen serumlevel was 28.5 ng/dL (range 1 to 4,448 ng/dL). Neoadjuvantchemotherapy was used in 24 (26.4%) patients similarlydistributed in both groups.

The mean number of nodules was 2.9 (range 1 to 10),with 29 (31%) patients having more than 3 nodules. Themean size of the largest lesion was 5.2 cm (range .5 to 23.5cm). In 88 cases (96.7%), tumor differentiation was grade Ior II; in 3 cases, it was grade III. The mean follow-up timefor the entire series was 2.8 years (range 1 to 8.5 years),whereas the mean follow-up for survivors was 4.7 years.

Table 2 Univariate logistic regression analysis: risk factors for over

Variables P value

More than 3 lesions .08Infiltrative tumor growth pattern .11R1 margin .20Metacronous diagnosis of metastasis .38Margins ,1 mm .39Pre-operative CEA .200 .54Biggest lesion .5 cm .62Age .55 years .63Margins ,10 mm .66Margins ,5 mm .83Egde hepatic ressection .84Poor grading .85Male sex .89

CEA 5 carcinoembryonic antigen; CI 5 confidence interval; OR 5 odds rat

Tumor recurrence was observed in 65 patients (71.4%),with a mean time of 9.5 months after hepatic resection.Extrahepatic recurrence was observed in 28 patients(43.1%) and intrahepatic recurrence in 37 patients(56.9%). In 10 patients (15.4%), local recurrence wasobserved.

Univariate logistic regression showed that the presenceof 3 or more lesions was the most important risk factor forrecurrence (OR5 3.92) followed by the infiltrative margintype (OR 5 2.13) although without statistical significance(Table 2). According to multivariate analysis, the presence

all recurrence

OR 95% CI

3.92 .83–18.442.13 .85–5.364.02 .48–33.441.50 .60–3.741.59 .56–4.55.66 .18–2.49.78 .30–2.06.79 .31–2.051.31 .40–4.281.11 .42–2.901.11 .43–2.86.79 .07–9.151.06 .43–2.65

io.

Table 3 Multivariate logistic regression analysis for risk factors of overall recurrence and intrahepatic recurrence

Variables P value OR 95% CI

Overall recurrence*More than 3 lesions .05 5.14 1.01–26.43Infiltrative tumor growth pattern .05 2.81 1.00–7.96R1 margin .27 3.92 .35–43.92Margins ,1 mm .74 1.23 .35–4.40

Intrahepatic recurrence†

Infiltrative tumor growth pattern .02 3.50 1.18–10.41R1 margin .15 4.00 .60–26.77More than 3 lesions .24 2.03 .62–6.65Margins ,1 mm .48 .60 .14–2.52

CI 5 confidence interval; OR 5 odds ratio.

*Hosmer-Lemeshow test: chi-square test 5 3.72; P 5 .88.†Hosmer-Lemeshow test: chi-square 5 2.65; P 5 .95.

496 The American Journal of Surgery, Vol 207, No 4, April 2014

of 3 or more lesions (P 5 .05; OR 5 5.14; 95% CI, 1.01 to26.43) and the infiltrative tumor margin type (P 5 .05; OR5 2.81; 95% CI, 1.0 to 7.9) were identified as independentrisk factors for recurrence (Table 3). Free tumor marginsless than 1 mm did not emerge as a significant risk factorfor recurrence. Patients with an infiltrative-type tumoralso had a significantly higher rate of intrahepatic recur-rence than patients with a pushing growth pattern (38.9%vs 16.2%, P 5 .02).

When survival analysis was performed for the entirepopulation, 5-year and disease-free survival rates were40.3% and 28.7%, respectively. In terms of disease-freesurvival rates, patients with an infiltrative-type tumorshowed a 5-year survival rate significantly inferior to thosewith pushing margins (20.2% vs 40.5%, P 5 .05, Fig. 2).No significant differences were observed among patients

Figure 2 Disease-free survival rates according to the tumorgrowth pattern of margin. Comparisons between groups were per-formed using the log-rank test.

categorized according to the number of lesions and a tumormargin less than 1 mm (Table 4).

Comments

An important issue when dealing with CRM resection issurgical margins. Previous studies have shown controver-sial results regarding adequate surgical margins; somegroups suggested margins of at least 1 cm10,17,18 and othersa free subcentrimetric margin.19–21

In the largest retrospective study addressing this issueincluding 1,019 patients who underwent CRM resection, Areet al10 observed better survival rates in patients with marginslarger than 1 cm. However, these authors reported that inmany patients resections with smaller margins (ie, ,1 cm)were associated with favorable outcomes. In a study with663 patients, Figueras et al21 observed that a margin thickerthan 1 cm was not an independent risk factor for recurrence.In amulticenter study of 557 patients, Pawlik et al22 found nosignificant difference in survival rates among patients withnegative surgical margins (R0) regardless of the width ofthe margin (1 to 4 mm). Moreover, in a large French study,de Haas et al23 emphasized that despite a higher recurrencerate in patients with R1 resection, survival rates were similarto those with a R0 resection. Our data found that when neg-ative (R0 resection), the margin size has no impact for eithersurvival or local recurrence.

This controversy regarding margin width leads to thehypothesis that other biological factors may be involved inthe pathophysiology of tumor recurrence. The primaryCRC tumor growth pattern is a prognostic factor forrecurrence. It can be classified as an infiltrative or pushingpattern in which patients with infiltrative tumors have ahigher incidence of local recurrence and metastases.11,12

Interestingly, this simple and inexpensive classificationwas not largely used for CRC pathological staging. How-ever, especially in an era where most studies look to the mo-lecular aspects of the tumor and margins, the concept ofbiological behavior by phenotypic tumoral edges analyses

Table 4 Disease-free survival analysis according to tumor growth pattern type, number of lesions, and margin distance

Variables

Disease-free survival

P value1 y 3 y 5 y

Tumor growth patternPushing 62.2 40.5 40.5 .05Infiltrative 53.0 28.6 20.2

Number of lesions%3 64.1 37.7 32.0 .09.3 44.4 16.7 16.7

Margin distance,1 mm 48.1 25.9 22.2 .21.1 mm 63.7 36.6 31.5

Comparisons between the groups were performed using the log-rank test.

R.S. Pinheiro et al. Tumor growth pattern and CRM 497

should be highlighted. Regarding liver metastasis, there isno well-established classification concerning tumor growthpatterns.

Few studies have evaluated similar classifications to theliver CRM growth pattern. Patients with CRC with pushingmargins had significantly better disease-free survival thanthose with infiltrative margins.12 Using multivariate analy-sis, Nagashima et al16 identified liver metastases with an in-filtrative growth pattern as a prognostic factor for shortersurvival. Moreover, Yamaguchi et al15 evaluated an infiltra-tive growth pattern as a predictor of survival after CRMresection and observed poor outcomes in this group ofpatients.

In the present study, we evaluated the impact of thetumoral edge growth pattern as proposed by Jass et al11

for colorectal cancer in the late 80s when they showedthat the tumor edge characteristic was 1 of 4microscopic-independent variables with an impact onprognosis. According to multivariate analysis, an infiltra-tive tumor margin type was an independent risk factorfor overall and intrahepatic recurrence. Overall recur-rence has shown a substantial 95% CI from 1.01 to7.96 with an OR of 2.81 for infiltrative margins. Evenwith a border line P value of .05, which is probablycaused by our small sample size, it strongly suggeststhat our hypothesis is valid. When we observed only in-trahepatic recurrence, infiltrative margins became astronger risk factor with a 95% CI from 1.18 to 10.41,an OR of 3.5, and a P value of .02. Five-year disease-free survival rates were significantly superior for patientswith pushing growth patterns (20.2% vs 40.5%, P 5 .05).

The advantage of this classification is the straightfor-ward stratification (pushing or infiltrative) diagnosed byhistological examination using hematoxylin-eosin stain.Conceptually, the tumor growth pattern may represent amarker of tumor biological behavior and may predict therisk of recurrence after liver resection, thus making pa-tients’ selection for aggressive adjuvant therapies andintensive follow-up easier. Indeed, infiltrative marginsproved to be a significant risk factor not only for recurrencebut also for overall and disease-free survival. Although the

general recommendation is that a wide (ie, larger than1 cm) resection margin should remain the goal, an antic-ipated subcentrimetic margin, although not ideal, shouldnot be a contraindication for resection. In light of ourfindings, one may hypothesize that wider surgical marginsin patients with infiltrative margins would lower theintrahepatic recurrence risk; however, this has yet to beproven.

Our study has some limitations, mainly because of thesample size, which is relatively small. Obviously, it did nothelp us in the construction of complex prognostic models;however, it may be useful to call attention to an importantprognostic factor in primary CRC that correlates with CRChepatic metastasis. The use of the tumor edge classificationcan help to demystify the wide variations of surgical margindata, but further studies are required to elucidate thishypothesis.

In conclusion, patients with CRM presenting with apushing tumor growth pattern have better disease-freesurvival rates and less intrahepatic recurrence comparedwith patients with infiltrative tumors. The adoption ofgrowth patterns can represent a useful tool to improveselection criteria for adjuvant therapy. Further studieswith larger data sets and longer follow-ups are neededto elucidate the potential selective power of thisclassification.

Acknowledgments

The authors thank the Department of Pathology of theUniversity of Sao Paulo Medical School for the histologicalrevision of all surgical specimens.

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