Pancreatic endosonograph y: Clinical TNM compared to...

BILIARY TRACT AND PANCREAS

Pancreatic endosonograph y: Clinical TNM staging compared to histology

TL TIO, MD, Pl 1D

ABSTRACT: Endosonography has been reported to be effective in the staging of gastrointestinal carcinoma. Pancreatic carcinom::i ts included in the new (1987) TNM classification. Rcscctability is abandoned in favour of depth of tumour invasion. In the author's preoperative study, endosonography was ac• curale for staging of tumour catt>gories, anJ early stages of disease could be distinguished from advanced carcinomas. The presence or absence of regional lymph nodes can be detected. Tissue diagnosis hy biopsy and endosonographyguidcd cytolob'Y is now possible. This imaging technique will become the standard procedure for the staging of pancreatic carcinoma. Can J Gastroenterol 1990;4(9):57l-575

Key Words: End.osonograJ)hy, Hiswlogy. Pancreatic carcinoma, TNM staging

L' endosonographie pancreatique: La classification TNM clinique comparee a l'histologie

RESUME: On a rapportc l'efficac1te de l'endosonographie dans la classification des cancers gastro-intestinaux. Le cancer du pancreas relcve maintenant de la nouvelle classification TNM (1987). La rcsecabilite a etc abanJonnce et fait place a la profondeur de !'invasion tumorale. Dans notre etude prcopcrawire, l'endosonographie a perm is la classification exactc de.s categories de tumeurs; elle a egalement aide a Jistinguer !es cancers aux premiers stades de leur evolution, des canccn; avances. La presence ou !'absence d'extension aux ganglions lymphariques a ete decelee. Le diagnostic portanr sur les tissus preleves par cytoponction a l'aiguille echoguidee est desonnais possible. Cette techni4uc d'imagerie deviendra la procedure standard Jans la classification des cancers du pancreas.

CONVENTIONAL ABDOMINAL

ultrasound is a standard imaging technique for evaluation of patients with pancreatic diseases. This procedure, however, is often hampered by rhe presence of bowel gas and adipose tissue. Endoscopic retrograde cholangio-

pancreatography (ERCP) is accurate fo r the detection and stag ing of pancreatobiltary abnormal itics. Endoscopic ul trasonography, genera lly known as endosonography, was developed to improve sonographic images by direct approach co the target of

Academic Medical Center, Department ofGascroenr.erology-HeJ)atology, Amsterdam, The Netherlands

Correspondence and re/mnt.1: Dr TL Tiu, Acadenuc Medical Center, Department of Gascroenterology-Hepacology, Meihergdreef 9, l l 05 AZ Amsterdam, The Nerherlarul.s. Telephone 020-566-9111. Fax 020-566-4440

interest via the gastrointest inal lumen {1-9). Recently, staging of pancreatic carcinoma has been included in the new (1987) TNM classifica ti on ( 10, 11 ). In a prospective stuJy, endosonography was performeJ preopcrat1ve I y to assess the accuracy and limitations of cndosonography in the TNM staging of pancreatic and ampullary carcinoma.

INSTRUMENTS For pancreas endosonography the

author has been using Olympus echoendoscopes EU-M2 and EU-M3. The latter emits a switchable fre4uency of 7.5 or 12 MHz and a biopsy channel for cndosonography-guided cytology or biopsy or v1deoechocndoscope (VUM2) (Figure I) . Recently, a small catheter echoprobe which can be introduced into the biopsy channel of a forward-viewing large calibre gastroscope became avai lable (Figure 2). The specifications of these instruments are summarized in Table I.

INVESTIGATION TECHNIQUES

The transgastric approach ,1 llows clear imaging of the body and tail of the pancreas because of the topographic anatomical relationship between the stomach and pancreas (Figure 3 ). For examinatton of che entire head of the pancreas, a transduodenal approach is usually necessary. The configuration of the stomach plays a crucial role for imaging of che pancreas. A long extended

572 CAN J GASTROENTEROL VOL 4 No 9 DECEMBER 1990

Pancreatic endosonography

Figure l) An OlymJJUS prototype videoechoeruloscope (VU-M2) with a small echoprobe (e) attached at the tip of a side-viewing duodenoscope (11) . Note the smaller diameter of the echoprobe compared tO the gastrnscope

Figure 2) An Olympu., />rototyf,e catheter echoprnhc ( e), which can he introduced through the instrumental channel of a large calilrre ga.mosco/1e

TABLE 1 Technical data of various Olympus echoendoscopes Echoendoscope EU·M2 EU·M3 VU·M2 (video) Catheter echoprobe Endoscope Side-viewing Side-viewing Side-viewing GIF-ITlO I GIF-IT20 Echoprobe length 42 mm 42 mm 44 mm 140 cm (catheter) Diameter 13 mm 13 mm 10.4 mm 3 mm Frequency 7.5 or 10 MHz 7.5 MHz/ 12 MHz" 7.5 MHz 7 MHz Depth of penetration 10 cm 10 cm/ 3 cm 10 cm 3 cm Axial resolution 0.2 mm 0.2 mm / 0.12 mm 0.2 mm -0.2-0.3 Tile catheter echoprobe Is radial scanning. while oil echoendoscopes ore mechonlcol radial scanning (I 8d5 or 36lf ). Only the EU-M3 hos copob/1/ty for endoU/trosonogrophy-gulded puncture or biopsy. "Switchable frequency

Figure 3) Anatomic scheme (pnstenar view) shows the relationship between the stomach and the surrounding orgam. sp Spleen; lk Left kidney; P Pancreas; l Liver

stomach provides clear imaging of the entire pancreas. In the case of stomach after partial resection (Billroth I or II}, adequate imaging of the pancreas is difficult or impossible. Patients after a

Figure 4) Endosonogram of a hypoechoic pancreatic carcinoma (t) obstructing the common hile duct ( cbd) and pancreatic duct ( pd) , a 'double duct lesion.' In Lymph nodes suspected of meta.~tascs

total gastrectomy should not undergo endosonography because the pancreas cannot he visualized sonographically.

The most important landmark for a transgastric approach is the splenic vem, which is localized dorsally adjacent to the body and tail of the pancreas. The entire ~plen ic vein can be followed from the splennportal con-

CAN] GASTROENTEROL VOL 4 No 9 0ECEMRER 1990

fluence to the splenic hilum. By the transduodenal approach, the head of the pancreas is imaged between the duodenal wall and the mesenteric vessels. Cross-sectional images ana logous to computed tomography should be made for standardization of cndosonography images.

INTERPRETATION OF ENDOSONOGRAPHIC IMAGES

The interpretation of pancreatic carcinoma is comparable to transcutaneous ultrasonography. For classifying ductular abnormalities, criteria used for the interpretation of ERCP must be incorporateJ. A pancreatic carcinoma is imaged as a hypoechoic tumour usually obstructing the main W irsung duct associated with a prestenotic dilatation of the pancreat ic and common bile ducts. Thus, the cause and extent of the 'double duct lesion' can be imaged (Figure 4). Occasionally intraducrnl tumours originating from the wall of the pancreatic duct can be found. The intraducral polypoid pat-

571

TIO

TABLE 2 Endosonography criteria for 1987 TNM classification of pancreatic carcinoma T Primary tumour Tl Hypoecholc tumour limited to the

pancreas Tl a Tumour 2 cm or less in greatest

dimension Tl b Tumour more than 2 cm in

greatest dimension T2 Hypoechoic tumour extends

directly to any of the following: duodenum. bile duct. peripanc reatlc tissue

T3 Hypoechoic tumour extends to any of the following: stomach, spleen. colon. adjacent large vessels

Tx Primary tumour cannot be assessed N Regional lymph nodes NO No regional lymph node metastasis Nl Regional lymph node metastasis Nx Regional lymph nodes cannot be

assessed M Distant metastases MO No distant metastases M 1 Distant metastases: Hepatic

metastasis, peritoneal dissemination

Mx Distant metastases cannot be assessed

Figure 5 ) Endosonogram of an early pancreatic carcinoma (T) extended into the dilated pancreatic duce (PD). P Pancreas; SV Splenic vein

tern may represent proliferation of the epithelium of the pancreatic duce or the carcinoma itself. Recently, pancreatic carcinoma was incorporated into the new ( 1987) TNM classification (Table 2).

Staging of distant metastases, however, should be excluded due to the limited penetration depth of ultrasound. Therefore, liver metastases and peritoneal dissemination may not be imaged.

574

Figure 6) A Endosonogram of extensive pancreacic carcmoma (1) wuh retroperitoneal extension adjacent tO the aorta (ao). cv Cava! vein; In Lymph nodes suspected of metastases. B Corresponding computed tomography shows a tumour mass ( t) extending co the aorta ( ao) . cv Cava/ vein; msa Mesenter1c superior arc:ery; sc Stomach; d Duodenum

CLINICAL TNM ST AGING Pancreatic head carcinoma usually

causes obstruction of the common bile duct. Thus, obstructive jaundice is the most common clinical symptom. The prognosis, however, remains poor despite advantages of diagnostic modalilies ( 12-14). The size and extent of pancreatic carcinoma may play an important role in the prognosis (15, 16). In contrast, obstructive jaundice due to carcinoma of the body and/or tail of the

pancreas is rare except when there 1s a very extensive rumour mass. Ampullary carcinomas, however, may cause obstructive jaundice even in the early stage of disease (17). The new (1987) TNM classification should he used for staging carcinomas of the head of the pancreas. Therefore, the common bile duct and duodenum are used as demarcation marks for T2 carcinoma. Early carcinomas are therefore more frequently expected to be found in the

CAN J GASTROENTEROL VOL 4 No 9 DECEMBER l 990

junction between the head and body of

ihe pancreas, or a distance from the common bile duct without symproms of

iaundice, eg, uncinare process. lnfil rrauon into the stomach is classified as a

T3 carcinoma. Moreover, infiltration into the aJjacent major bkxld vessels

(splenic vein, portal vein, splennportal

connuence, mesenteric vessel~. etc) can be clearly imaged hecause elf the real

ume character of ulrrasounJ anJ the

abili ty to position the echoprnbe

towards the target of interest.

Occasionally, portal hypertension with the presence of gastric vances be

cause of splenic or portal obstruction

can be found, which b usually a con

tra indication for tumour resection.

Early pancreatic carcinoma is defined as a Tl carcinoma (diameter less than 2 cm) with no evidence of lymph node involvement. Such small carcinomas

are rare anJ can be found incidenrally

Juring evaluation of patients with ah

dom inal discomfort (Figure 5). In

patients with obstrucuve Jaundice, the

stage of pancreatic carcinoma is usually

REFERENCES l. Tio TL, Tytgac GNJ. Endoscor1c

ultra,onography in the .i,,e:,:,ment of mcra- and transmural infiltration nf tumours in the esophagus, stomach and papilla of Yater and 111 the Jetecrmn nf extra-esophageal lesion. Endmcopy 1984;4:220-5.

2. Tio TL, Tytgat GNJ. Endoscopic ultra,onography in staging local rcscc , tability of pancreatic and pernimpullary malignancy. Scand J Gastroenteml 1986;2l(Suppl 123):135-42.

3. Tio TL, Tytgat GNJ. Endoscop1L ultrasonography in analys111g perimtcstmal lymph node abnormality. Preliminary results of srud1es 111 vitro and m vivo with histology. Scand J Gastroenterol J 986;2 I (Suppl I 21): 158-63.

4 Tio TL, T ytgar GN J. Adas of Tramintestinal Ulrra,onography. Aabmeer: Mur-Kostvcrlorcn, 1986.

5. Tio TL. Endosnnography m Gastroenccrology. Heidclherg, Berlin, New York, London, Tnkyo: Springer Verlag, l 988.

6. Yasuda K, Mukai 11, Cho E, Nakayima M, Kawai K. The use of endoscopic ultrasonngraphy 111 the dctcctmg and staging of carcinoma nf the papill,1 of

already advanced. In the authm's cli111-

cal experience of more than five years,

the incidence of lymph node involve

ment in Tl carcinoma is approximately

40% (9). This has also been reponec.l

elsewhere ( 14), and may reflect the

highly malignant nature of disease

(13,14). The incidence nf lymph node

metastasis increases with Lhc JcpLh of

tumour infiltratilm. In concrasr, the in

cidence in Tl ampullary carcinoma was 0% (9).

The accuracy rate of cndosono

graphy in diagnosmg regional lymph

nodes and distant mernstases is c.om

parable with that of esophagogastric

carcmoma (18,19). Endosonogrnphy is mnre accurate in diagnosing mernstatic

involvement than nonmetastatic

lymph nodes. This is of utmost impor

tance from the clinical pomt of view

because of the poor prognosis of the

disease. For the assessment of liver

mctastasi~, trnnscutancnus sonography

is necessary tn assess metastases in the

nght liver lohes anJ ro confirm diag

nosis by cyrolog1cal punc.rure.

Yater. Endmcnpy l 988;20:218-22. 7. Yasuda K. Mukai I[, Fujimoco S,

Nakay11na M, Kawai K. The diagnosis of pancreatic cancer by endoscopic ultrasonography. Gastromtesr Endosc l 988; 34: 1-8.

8. Tio TI,, Tyt1,,r.u GNJ. Endoscopic ultrnsonograrhy of nom1al ,md pathologic upper ga:,troi.ntcstinal wall stnicrure: Comparison of studies m v11ro with histolO!,')', Scand J Gastmcntcrol 1986;2 l (Suppl 123 ):27 -B.

9. Tin TL, Tytgat GNJ, C1kot RJLM. I louthoff I [J. Ampullopancrcatic car-cmomas: TNM stag111g w11 h en-dosonography. Radiology. (In pres,)

10. Hermanek P, Sobin LH. TNM Clas-sificat1on of Malignm1t Tumours. I nrer-nauonal Unwn Against Cancer, 4th cJn. Bt!rlm, Heidelberg, New York, London, Pans, Tokyo: Sprmger Verlag, 1987.

11 Sobin LH, Hermanck P, Hutter RP TNM classification of malignant tumnrs. Cancer 1988; 61:2310-4.

12. Cancer Faces and Figures 1987, New York. Am Cancer Soc 1987: 14.

I>. Mnoss11 AR. Pancreatic cancer: Ap-proach t<> diagnosing, selection fm surgery and chrnce of orcrnt1on. Cancer 1982; 50:2689-98.

CAN J GASTROENTEROL VOL 4 No 9 DECEMflER 1990

Pancreatic endosonography

CONCLUSIONS Endosonography will hccome an im

portant diagnostic procedure tor staging

pancreatic cancer. In 1he near fu ture ,

tissue diagnosis hy endosonngraphy

guidcd cytology of lymph nodes will

play an important role 111 planning

treatment strategics. ln the case of posi

t1 ve cyrnlogy, surgery will become unfavorable. Moreover, ampullary car

cinnma c.m he distmguished from a pancreatic carunoma, especially m the

early stages nf dise;:ise.

The clinical role of endosonogrnphy in the detection of early p;mcre,1ric car

cinomas 111 a nonselecred pupulmiun is

still unknown. At present, introduction

of endoscmography a:, a sLreening d1ag

nost1c modal icy appears to he utop1c

because of the invasive muure of the

procedure and the cost-benefit ratio. Endosonography will become the imag

ing technique of chrnce for staging pancreatic carcmomas hccause of its

ahi11ty to discriminate emly stage u1r

cinomas Imm aJvanced stages of dis

ease.

14. Cuhill.1 AL, former J, Fitzger.1ld J. Lymph node 1nvolvemenc 1n car-cinuma of the head of the pancreas mea Cancer 1978;4 I :880-7.

l'i. Tsuchiya R, Orihc T, Noda T. S1:c of the rumor and orhcr factor, mfluL·nc-mg prognn,i, ,if carcinoma ,if the head nf rhe pancrea,. Am J Gasrroenrerol l 985;80:459-62.

16. Tsuch1y,1 R, Noda T, I Lir,1da N, Cl ,ti. Collccuve review nf small carcinomas of the pancreas. Ann Surg l 986;20 ): 77-8 l.

17. M,1kipour I[ , C,x,pcrman A, [);111z1 JT, farmer RG. Carcinoma nf rhc ampulla of V.ircr: Review of 18 cases with emphasis of treatmt·nr and pmgnostlt focrnr1,. Ann Surg 1976; 183: 341-4.

18. TIO TL, Cohen r. Cocne PP, UJding J, den I lartog Jager FCA,R Tytgm GNJ. Endosnnogrnphy anJ com-putcd mmogn1phy of esophageal car-cinoma: Preopcrm 1ve ch1ssifica1 ion comp,1red to the new ( 1987) TN M classification. Gascrocncerology 1989;96: l 4 78-86.

19. Tl<l TL, Cocnc PPLO, Schouwmk Ml I, Tytgar GNJ. E.snphagogascric rnr-cinoma: Preoperative TNM cla,sifica-tHm with .:mlosonography. Radinlngy 1989;I 7Ml 1-7.

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