Journal of the Korean Radiologica l Society, 1994; 31(2) ; 301 -305

Staging of Advanced Gastric Cancer: Comparison of Conventional CT and Intraoperative Assessment1

Hyun Chul Rhim, M.D. , Yoon Young Choi , M.D., 0 Keun Bae, M.D.,

Jong Sung Kim, M.D., Byung Hee Koh , M.D.,

On Koo Cho, M.D. , Chang- Kok Hahm, M.D.

Purpose: We performed a retrospective study to compare the accuracy be ­tween conventional CT staging and intraoperative staging for advanced gastric cancer.

Materials and Methods: Sixty patients with advanced gastric cancer were in­cluded in this study during the recent 2 year-period. AII were pre- and posto­peratively diagnosed as advanced gastric cancer. CTwas performed with G E 9800 and Somatom DR3 under conventional technique in 50 and with others in 10 re­ferred patients. The CT staging for T and N category with emphasis on incurable factor , if not resected , were performed . And we compared the accuracy between conventional CT and intraoperative staging. The final histo-pathologic staging was used as a gold standard.

Results: Accuracy of CT and operation for T4(n=17) factor is 76.9 % and 86.2 % respectively. Overestimation rate for T4 was 9.3 % by CT and 6 .1 % by operation ,

and underestimation rate for was 13.8 % and 7.7 % respectively. Accuracy of CT and operation for N(n=60) factorwas 50% and 60% respectively. Overestimation rate for N factor was 18.3 % by CT and 18.3 % by operation , and underestimation rate for N factor was 31.7 % and 21.7 % respectively. Correct Tand N staging was possible only in 33% by CTand 38% by intraoperative assessment.

Conclusion: Conventional CT and intraoperative staging for incurable T/N fac­tor in advanced gastric cancer have a potential limitations, especially for N fac ­tor . Therefore, more reliable modality or technique such as dynamic scanning by spiral CT, transabdominal or endoscopic ultrasonography should be preopera­tively performed to complement infrequent errors in intraoperativestaging. Fur­thermore, a histology-oriented surgical approach seems essential in selecting the most appropriate surg ical procedure.

IndexWords: Stomach , neoplasms Stomach , CT Neoplasms, staging

INTRODUCTION

Accurate preoperative staging of gastric cancer is essential to plan appropriate treament whether it is surgical or non - surgical(1). However, accuracies of radiologic methods including computed tomography (CT) are still conflicting (2 , 6-16). Therefore , unnec­cessoryexpl이 aparotomy is still unavoidable.

'Department ofD iagnostic Radiology, Coll ege 01 Medicine, Hanyang University Received December8, 1993 ; Accepted June 20,1994 Address reprint requests to: Hyun Chul Rhim , M.D., Department 01 Diagnostic Radiology , College 01 Medicine, Hanyang University. 17, Haengdang-dong ,

Sungdong-ku ,Seoul , 133.792 Korea Tel. 82-2-293-2111 ,3111 Fax.82-2-291-9866

On the other hand , recent studies revealed frequent errors even in intraoperative assessment which has been considered as the most reliable and final staging method (16 -19). And Japanese Stomach Cancer Study Group is recently emphasing the importance of cura­tive resection and proposing the criteria of incurable factor , if not resected , in gastric resection(20).

In this study , we compared the accuracy of conven­tional CT and intraoperative staging for advanced gas­tric cancer with final patholog ic staging as a gold stan­dard.

MATERIALS and METHODS

In a 26 - month period , we retrospectively studied 60

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Journal 01 the Korean Radiologica l Society, 1994; 31(2) : 301 - 305

patients who had pathologically proved adenocar cin­oma of stomach. They consisted of 37 men and 23 wom­en (mean age ; 54 yeras , range ; 27 - 81 years). CT scans were performed with either GE 9800 (General Electric , Milwaukee, U. S. A.) in 38 patients or Somatom DR3 (Siemens, Erlangen , Germany) in 12 patients , and with other third generation CT scanners in 10 referred pati­ents. Scanning variables were 120 kVp , 240 mA, scann­ing time 2 sec for GE 9800 system and 125 kVp , 350 mA, scanning time 4 secfor Somatom DR3. Ten - millimeter thick contiguous sections with 3 mm interval were acq­uired from the diaphragm to the iliac crest. AII of 50 in­patients received contrast medium [a bolus 50 ml and a drip infusion 100 ml of Ultravist 300 (Schering , Germa­ny)] intravenously. AII of 50 inpa- tients received cont­rast medium (500 ml water in 38 patients , 500 ml Gas­trografin in 12 patients) orally before the CT procedure.

AII CT scans were reviewed in respect to depth of in­vasion of primary lesion and Iymph node metastasis by two radiologists (H. C. R. , Y. Y. C.). Especially we fo­cused on the incurable T/N factor (T4 or any N) , if not resected , according to criteria of curative resection by Japanese Research Society for Gastric Cancer (20). T4 criteria on CT was defined as obliteration of fat plane between primary lesion and adjacent organ. T2 and T3 were considered as a single category because differ­entiation of two was very difficult by conventional tech­nique. Total number of T lesions was 65 in 60 patients , including double T41esions in 5 patients.

Lymph node metastasis were evaluated as following criteria ; NO (No metastasis) , N1 (perigastric Iymph nodes), N2(left gastric , common hepatic, splenic , celiac artery Iymph node) , and > N2(the other intraab­dominal Iymph nodes). Lymph nodes were considered positive if they exceed 10 mm in greatest diameter. The results of CT and intraoperative surgical staging for

Fig .1 . Hepatic invasion Contrast-enhanced CT scan shows obliteration 01 lat plan e (white arrow) between 01 gastric mass and lateral segment 01 liver with adjacent locallow-attenuation lesion (b lack arrow); true positive on CT and operation

T/N factor were compared with final histo -pathologic staging.

RESULTS

Accurate estimate for T4 factor was possible in 76.9 % by CT and 86.2 % by intraoperative staging(Fig. 1) Overestimation rate for T4 was 9.3 % by CT and 6.1 % by operation , and underestimation rate was 13.8 % and 7.7 % respectively (Table 1 )(Fig. 2, 3) . Pathologically proven T4 factors were invasion to pancreas(n= 10) , transverse colon(n= 5) , and liver(n = 2)(Fig. 2, 3) . Esti­mation of N status was accurate in 50 % by CT and 60 % by intraoperative staging. Overestimation rate for N was 18.3 % and 18.3 %, and underestimation rate was 31 .7 % and 21.7 % respectively (Table 2)(Fig. 4). Cor­rect T and N staging was possible in 33 % by CT and 38% by intraoperative assessment (Table 3).

DISCUSSION

An accurate preoperative staging of the most import­ant prognostic factor of gastric cancer , such as depth of

invasion(T) and Iymph node metastasis(~ιfor pl anning of appropriate treatment(1) , because over­

estimation may result in an unduly conservative oper­ation and reduce the likel ihood of cure, whereas under­estimation may lead to inappropriate radical surgery with risk(13)

The previous reports on the accuracy of conven­tional CT staging is somewhat conflicting(6 -16). Five out of twelve papers revealed pessimistic conclusions for CT’s role(2 , 13 -16) , while seven found CTto be use­ful(6 -12). Major limitations of these optimistic data lie in retrospective evaluation with small sized materials and comparison with intraoperative surgical assess­ment as a gold standard. But recent prospective stu­dies using pathologic staging as a gold standard has shown the low accuracy of conventional CT and intra­opertive staging(19). Our data has shown the agree­ment with recent pessimistic views for the role of pre ­operative conventional CT staging(2 , 13 -16). Their accuracies for T and/or N categories ranged from 45 % to 56 %, which were comparable with ours.

Accuracy for T in our study seems to be higher than

Table 1 . Staging lor T Factor : CT versus Operation

CT

T2 /3 T4

42 6

9 8

76.9 9.3

13.8

4 10

86.2

6.1

7.7

OPERATION

T2 /3 T4

PATHOLOGY (n) T2 / 3(48)

T4 (17)

Accurate( %)

Overstage( %)

Understage( %)

46 5

U 「j

Hyun Chul Rhim, et al : Stagin g of Advanced Gastric Cancer

a b Fig. 2 . Pancreatic invasion

a. Contrast-enhanced CT scan shows obliteration 01 lat plane (arrows) between gastric wall and pancreatic head ; lalse positive on CT and true negative on operation

b. Contrast-enhanced CT scan shows ob literation 01 lat plane (arrows) between gastric wall and pancreatic head ; true positive on CT

and lalse negative on operation

a b Fig. 3 . Transverse colon invasion

a. Contrast-enhanced CT scan shows suspicious colonic wall thickening (arrowheads) without signilicant adjacemt omental inliltration

probably due to collapsed bowel ; lalse negative on CT and true positive on operation

b. Contrast-enhanced CT scan shows suspicious colonic wall thickening (arrows) with prominent adjacemt omental inli ltration prob-

ably du e to colonic invasion ; lalse positive on CT and true negative on operation

those of previous studies , because we excluded early Table 2 . Staging for N Factor: CT versus Operation

gastric cancer and considered T2 and T3 as single CT OPERATION category due to difficulty of differentiation between T2

NO N1 N2 ) N2 NO N1 N2 ) N2 and T3 by conventional C T. The criteria for T4 factor by

CT is not reliable because the source of errors is un- PATHOLOGY (n)

avoidable ifthe patients is emaciated or the perigastric NO( 6) 5 0 0 2 2 o 2

inflammation around tumor is present. Endoscopic N1 (24) 7 8 7 2 3 16 4

ultrasonography for T4 factor by Ziegler et al(19) N2(17) 0 5 11 4 10 2

revealed high sensitity(89%) , compared with conven- N3(13) 0 6 6 0 3 2 8

tional CT(44%) and intraoperative surgical assess- Accu rate( %) 50.0 60.0 ment(22 % ). Overstage( %) 18.3 18.3

Accuracy of conventional CT for overall N staging ac-Understage( %) 31.7 21 .7

cording to NO, N1 , N2, and ) N2 was 50 % , which was

m

ω

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Journal of the Korean Radiological Society, 1994 : 31(2) : 301 - 305

a b Fig. 4. Lymph node metastasis a. Contrast-enhanced CT scan shows equivocallow - attenuation lesion(arrow) , considered as partial volume effect of pancreas ; false negative celiac nodes on CT and true positive on operation b. Contrast-enhanced CT scan shows 1.5 cm sized , ovoid low - attenuation lesion adjacent to portal vein(arrow) ,suggested as hepatoduodenallymph node ; true positive hepatoduodenal node on CT and false negative on operation

similar to other results. But our results revealed high underestimation rate in contrast to other reports(12 , 19). It is suggested that the criteria of Iymph node in­volvement could have influenced on the difference. It deems neccessary to define more sophisticated cri­teria other than size category , including shape, multi­plicity , inter- nal texture , or relation to the tumor mass.

Another purpose of this study is to assess the re-liability of intraoperative surgical assessment. Intra­operative estimation of tumor infiltration and Iymph node metastases usually serve as major guidelines for decision about which operation should be performed in patients with gastric carcinoma. Type and magnitude of errors of intraoperative surgical staging in gastric can­cer might be negligible if preoperatively conventional diagnostic procedures such as UGI , endoscopy, ultrasonography, CT were able to give a reliable infor­mation on extent of tumors(17). Recent studies by Rhode , Madden , or Ziegler pointed outthe possibility of errors in intraoperative staging by comparing with histo - pathologic staging as a gold standard (16 -19). Rhode described that su rgical errors in staging depended on innumerable factors ; 1) . surgeon ’s atti­tude towards staging 2) type of standardization or methods 3) difficulty to differentiate not advanced from more advanced at laparotomy and to ascertain the de­gree of invasiveness of advanced tumors 4) difficulty or, rather impossibility of differention between invaded and non - invaded structures , especially ifthere is a lot of inflammatory tissue surrounding the primary tumor (1?). Our data, which showed low accuracy with con­siderable over - or underestimation rates of intraope­rative staging , support their opinion . Therefore , intrao­perative staging alone could be insufficient in selecting the best surgical procedure for i ndividual patient(19)

Table 3. Staging for T and N Factor

T + N

CT Operation

Accurate (%) 32.0 % 38.5 %

Overstage (%) 26.0 % 20.0 %

Understage (%) 42.0 % 41 .5 %

This study showed two points; 1) the significant limitations were found in accurate T/N staging for gas­tric cancer by conventional CT, similar to recent pessi­mistic results , 2) the considerable errors are possible by intraoperative assessment without standardized frozen section

In conclusion , conventional CT staging in advanced gastric cancer has potential limitations as well as intraoperative surgical assessment. Therefore , more reliable modalities or techniques such as dynamic scanning by spiral CT, high - resolution transab­dominal , or endoscopic ultrasonography are required to complement a possible errors in intraoperative macrospcopic staging. Furthermore , histology - orien­ted surgical approach with standardized frozen sections ofT/N factor during operation seems essential for selecting the most appropriate surgical procedure , whether the aim of operation is curative or pall iative

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7. Balle DM , Koehler RE, Karlstaedt N, Stanley RJ , Sagel SS. surgical staging in patients with cancer 01 the stomach. Scand J

Computed tomography 01 gastric neoplasm. Radiology 1981 Gastroentero/1987 ; 22: 27-30

140:431-436 18. Madden MV, Price SK, Learmonth GM , Dent DM. Surgical

8. Dehn TCB ‘ Rezek IB , White FE. The pre-operative assessment 01 staging 01 gastric carcinoma: sources and consequence 01

advanced gastric cancer by computed tomography. Br J Surg errors. Br J Surg 1987 ; 74 : 119-121

1984 ;71 :413-417 19. Ziegler K, Snaft C, Zimmer T, et al. Comparison 01 computed-

9 서형심 ， 이재섭 ， 이종진 등 위암환자에 있어서 전산화 단층촬영술의 tomography, endosonography, and intraoperative assessment

진단적 으|의 대한방사선의학회지 1985 ; 21 : 105-113 in TN staging olgastric carcinoma. Gut1993 ; 34: 604-61 0

10 신지열， 심전섭 ， 김병영 등 전산화단층촬영술에 의한·우|암의 수술전 20. Japanese Research Society lor Gastric Cancer. The general

병기결정의 의의 대한방사선의학회지 1989 ;25:741-747 rules 01 gastric cancer study 12th ed 金原出版械합會社 1993 ;

11 노병석 ， 임 덕 ， 김기환등 CT를이용한위암의훼장침습에대한판정 32-33

대한방사선의학회지 1990 ; 26 : 1 02-1 06

대한방사선의학회지 1994; 31(2): 301-305

진행성 위암에 대한 병기결정 :고식적 CT와 수술상 병기결정의 벼교

한양대학교 의과대학 진단방사선과학교실

임현철·최윤엉·배오근·김종성·고병희·조온구·합창곡

목 적:진행성 위암의 병기결정에 있어서 비절제시 치유불가인자로 알려진 T4및 N을중심으로 고식적 CT 및 수술상의 병

기결정의 성적을 후향적으로 비교하여 술전 및 술중 병기결정의 유용성 및 문제점을 알아보고자 하였다.

방 법 . 최근 2년동안 진행성 위암으로 진단받아 위절제술을 받았던 60명의 환자를 대상으로 하여 고식적 CT검사상 및 수

술중 육안적으로 평가한 병변의 침윤도(T)와 임파선 전이 정도(N)에 대하여 후향적으로 평가하여 이를 최종병리학적 병기

를 기준으로 각각의 정확도를 비교분석하였다.

결 과 : 병변의 침윤도에 대한 즉， 인접장기 침범 (T4)에 대한 CT 및 술중진단의 정확도는 각각 76.9 % , 86.2 % 였으며， 과

대평가는 9.3 %. 6.1 % 였고 과소평가는 13.8 %. 7.7 % 였다. 임파선 전이정도(N)에 대하여 CT 및 술중진단의 정확도는 각

각 50 %와 60 %였고 과대평가는 공히 18.3 % 과소평가는 각각 3 1.7 % 와 2 1.7 % 였다. 한편 병변의 침윤도 및 임파섣 전이

정도를 모두 정확히 평가가 가능했던 경우는 CT로는 33%에서 술중에서는 38%에서 가능하였다.

결 론:고식적 CT어| 의한 진행성위암의 병기결정은 비절제시 치유불능인자로 여겨지는 주변장기로의 침범유무(T4)에 대

해서는 어느정도의 유용성을 견지하고 있으나 임파섣 전이의 평가에 있어서는 낮은 정확도를 보였고， 이러한 문제점은 최종

병기결정 방법인 술중 병기 평가상에서도 내재되어 있음이 확인되었다. 따라서 현행의 고식적 CTOI상의 보다 신뢰도 높은

술전 방사선학적 진단법으로의 전향이 필요하며，술중 병기결정의 정확도의 향상을위한다각적인 노력도이어져야 할것으

로판단한다.

%

1994년도 춘계학술대회 증례퀴즈( III )

Case 4. F/30 C.C. ; intermittent neck pain since

2 months ago

Answer ; neurenteric cyst of C-spine

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