Polyps in a Low-risk Colonic Cancer Population in Colombia,

South America*

CARt.OS Rt.'STRI-:PO, M . D . , PELa'~'O CORR,:A, M.I . ) . ,

Er)(;AR DuQvs M. I ) . , CARt.OS CI_:I-:I.LO, M.D.

Restrepo C, Correa P, Duque E, Cue l lo C. Po lyps in a low-risk c o l o n i c cancer popu la t ion in Colombia , South A m e r i c a . Dis Co lon Rectum 1 9 8 1 ; 2 4 : 2 9 - 3 6 .

Co lon ic po lyps were systemat ica l ly searched for in 508 speci - m e n s co l lected from unse lee ted autops ies in indi~ iduats more than 10 years of age from MedeUia , Colombia, a l ow- inc idence geographic reg ion for colorectal cancer. A d e n o m a t o u s po l yps have a low preva lence rate in both sexes , comparable to that found in Call, Colombia and other populat ions with low risk for cancer. They were found more frequent ly in the right s ide of the co lon and are rare in the s igmoid co lon . They b e g i n to appear in the third decade of l i fe in both sexes . Prevalence rates for s ing le and mul t ip le po lyps increase wi th age in both s exes , males show- ing h igher rates than females at every age group. A d e n o m a t o u s p o l y p s in this populat ion are nsuaUy less than 3 mm in d iameter and do not show" v i l lous changes or epi thel ia l atypia. Hyperp las - tic p o l y p s were more frequent ly observed than a d e n o m a t o u s p o l y p s and rates s h o w a progress ive increase with age in both sexes . Mult ipl ic i ty also increases with age. Most p o l y p s are lo- cated in the low rectum and s i g m o i d fo l lowed by the c e c u m and ascend ing co lon . U s u a l l y hyperplas t ic po lyps are smal ler than 3 rum in d iameter and do not show epithel ia l atypia. Juven i l e po lyps were in frequent ly found in this series because ch i ldren less than l0 years o ld were e x c l u d e d . Divert icular d i s ease was also rare and, when found, was not associated with adenomatous po lyps . The assoc iat ion between adenomatous po lyps and co lonic cancer is d i s cus sed based on f ind ings in this report. [Key words: Potyp{s), co lonic; Colon; Ep idemio logyj

COLONIC CANCER iS the m o s t c o m m o n f o r m o f gas- trointestinal cancer in the United States and in some other countries in Europe and Oceania. Burkitt has observed a close relationship between s tandardized incidence rates o f colon cancer in men and economic development of the countries. ~ Al though the inci- dence rates for colonic cancer are low in Colombia,

* Received for pubIicatiop May 5. 1980.

This lesearch is supD;rted it! pa~t by Public Health Research Contracts N01-CP-53521 and N01-CP-3!~286 from the Division of Cancer Cause and Prevention, National Can.cer I.nstitttte. ~,Ath the l.ouisiana State University Medical Center. and Fundaci6n para la Educacion Sttperior.

Address reprint requests to I)r. Correa: Department of Pathol- ogy. l..ouisiana Stare L'ni~ersitv Medical Center, New Orleans. I.ou{siana 70112.

From the Departments c j Pathos Luuisia,la State Unk,ersity Medical Center,

New Orlea~2s, l.ot~isiana, atzd School of Medic,~e,

Unh.,ersidad del Valle, Call Colombia

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

some recent studies have shown a socioeconomic gra- dient with a four-fold greater- than-average cancer risk in the upper classes o f both sexes, e'a The in- creased incidence of cancer in high-risk populations appea r s to be due to a h i g h e r n u m b e r o f cases o f c a n c e r in i n t e r m e d i a t e par t s , s i g m o i d co lon and u p p e r rec tum but not in the cecum or lower r ec t t l r i i . 2 ,3

The premalignant role of polyps has been a subject of controversy in the past. Recent evidence derived f r o m pa tho log i c and e p i d e m i o l o g i c s tudies has s t r o n g l y s u g g e s t e d a s equen t i a l l ink be tween adenomatous polyps and cancer of the co lon? "a Pre- vious studies to determine the prevalence o f polyps in unselected autopsy specimens have been carried out in o ther cities in our count ry (Call, Colombia) as well as in other Latin American countries, in Hawaii and in the continental United States. ~-*" Based on such studies, an epidemiologic model for colonic cancer has been proposed, assigning a premal ignant role to adenomatous polyps, whose malignant t ransforma- tion would be influenced by envi ronmenta l factors and anatomic location. ~:''~4

Recent data f rom a cancer registry in Medellin, Co-- lombia, based on cases of- cancer diagnosed a m o n g affiliates of Insti tuto Colombiano del Seguro Social, show that cancer o f the colon and rec tum has low incidence rates in both sexes. The age-adjusted rates (world population), being 6.46 [or males and 0.72 for females, are slight b lower than those found it~ Call. 'a

This report describes the prevalence of the differ- ent types of polyps observed in consecutive atttopsies in Medel]in, Colombia. Findings are compared witb

01)12-3706'8ii0100/0029 $00.90 (~: Amcricari Society of t 'olon and Rectal Surge~)ns

29

DI~. Col. & Reel. 30 R E S T R E P O . 1:2'1" .-kl.. Jam-Feb. 1981

anatomic distribution of cases of colonic cancer seen in the same populat ion and with polyps prevalence r a t e s o b s e r v e d in o t h e r h igh - a n d low-r i sk populat ions.

Materials and Methods

A total o f 529 specimens was obta ined f rom con- secutive autopsies of persons over 10 years of age in the M6dico-I~egal Service and in the D e p a r t m e n t o f Pathology, Univers idad de Ant ioquia , d u r i n g the years of 1971 and 1973. T h e specimens included the terminal por t ion o f the small intestine, ileocecal valve and the anorectal junct ion. After washing, the speci- mens were fixed in 10% formalin /'or four days and carefully inspected by one of us (CR) u n d e r an il- lumina ted magni fy ing lens following the methods de- scribed by Cor rea el al. ~ All lesions were identified separately, measured , and their locations de t e rmined by gross a s s ignment o f s egm en t involved and by m e a s u r i n g the d i s tance in c e n t i m e t e r s f r o m the ileocecal valve (ICV) or the pect inate line in the anorectal junct ion. Each lesion was excised, e m b e d - ded in p a r a f f i n , s e c t i o n e d a n d s t a i n e d wi th hematoxyl in /eos in for microscopic stud?. T h e total length of the colon between ICV and pect inate line was recorded. Twen ty -one specimens were exc luded f rom the study because of severe autolysis, leaving a total n u m b e r of 508 (300 males and 208 females) cases which were used for this repor t .

Microscopically, the lesions were classified indi- v i d u a l l y by t h r e e p a t h o l o g i s t s f o l l o w i n g well- established criteria. ~6 Most of the cases were classified unanimously by all three pathologists, but for cases in which opinion was divided, the final classification was reached by consensus. Polyps were classified into adenomatous , hyperplastic, juveni le and miscellane- ous lesions. Adenoma tous polyps (adenomas) were def ined as having loci o f prol i fera t ion o f intestinal

epithelial cells a r r a n g e d in tu~)ules, without promi- nent InucoklS secretion and showing large, e longated, c r o w d e d , h y p e r c h r o m a t i c nucle i . ~7 H y p e r p l a s t i c polyps consisted of focal aggregat ions o f e longa ted glands f o r m e d bv cells with eosinophilic cytoplasm and enlarged n o r m o c h r o m a t i c nuclei. T h e r e were in- toldings of g landular lining and thickening of base- ment m e m b r a n e , ts Juveni le polyps were those show- ing cystic glands, ben ign g l a n d u l a r p ro l i f e ra t ion , p r o n o u n c e d stromal prol i fera t ion with f requen t ul- cerat ion and p r o m i n e n t i n f l ammato ry changes? 9

No cases o f villous or t ubu lopap i l l a ry a d e n o m a were found in the present series. No cases o f car- c inoma were encoun te red . Forty-two o f the lesions observed grossly as polyps were classified u n d e r the microscope as nonepi the l ia l in origin. I nc luded in this g r o u p were i n f l a m m a t o r y p o l y p s (28 cases) . pseudopolyps (4 cases), l e iomyoma (1 case), submuc- ous l i pomas (8 cases) , a n d h a m a r t o m a (1 case). I typerplas ia o f the lymphoid follicles was a c o m m o n finding a m o n g chi ldren 10 to 14 years of age.

T h e total length of colon varied mainly with age. T o avoid problems of compar i son , results conce rn ing the location of lesions 22 cm above the pect inate line are expressed in terms of relative distance f r o m ICV as suggested by C o r r e a et al. r

Results

T h e r e were 102 specimens positive for all types of polypoid lesions (20.1 per cent) o f the total n u m b e r of 508 cases collected, c o r r e s p o n d i n g to 59 males (19.7 pe r cent) and 43 females (20.7 per cent) (-Fable 1). Tab le 2 shows age- and sex-specific prevalence rates t o t the three types o f polyps. T h e overall prevalence o f adenoma tous polyps is abou t the same in males and females. T h e r e is an increase in rate with age in both sexes. Rates for mult iple a d e n o m a t o u s polyps show also a progressive increase with age in men, bu t in-

TABLE 1. Number of Specimens Collected and Positives for All 7~vpes of Lesior~--Medellin, Colombia (1971-73)

Age Group (years)

Males

Total Number

Positive

Number Per Cent

Females

Total Number

Positive

Number Per Cent

Both Sexes

Total Number

Positive

Number Per Cent

10-19 63 7 11.1 36 1 2.8 99 8 8,1 20-29 68 14 20.6 43 10 23.2 111. 24 2t.6 30-39 48 5 10.4 39 8 20.5 87 13 14.9 40-49 32 6 18.7 35 11 31.4 67 17 25.4 50-59 37 8 21.6 21 8 38.1 58 16 27.6 60 and over 52 19 36.5 34 5 14.7 86 24 27.9

TOTAL 300 59 19.7 208 43 20.7 508 102 20.1

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crease with age in minimal for women. Hyperplas t ic polyps show a higher prevalence in women. T h e y are more frequent and a p p e a r earlier than a d e n o m a t o u s polyps in both sexes. Both single and mult iple rates for hyperplas t ic polyps increase with age in bo th sexes, but an age gradient is riot seen a m o n g women af ter the age of 65. Juveni le polyps were rare in this sample mainly because chi ldren t inder ten years o f age were excluded f rom the collection. T h e y were mainly found in men and women unde r the age of 4.t y e a r s .

Coex i s t ence o f a d e n o m a t o u s and h y p e r p l a s t i c polyps was observed in 18 specimens (3.5 pe r cent o f all cases) arid mainly in men older than 45 years (Table 3).

T h e majori ty of patients had single polyps, except for a d e n o m a t o u s pol~ps in males, in whom mult iple polyps were as f requent ly seen as single polyps, with an average of 2.05 po lyps /person (Table 4). This fig- ure is slightly lower than the co r re spond ing value ob- served in Call and definitely much lower than in New Orleans. ~'r In women, however, adenoma tous polyps occur red mainly as single lesions. Juven i le polyps were found ahnost exclusively as single lesions in this sample.

Polyps encoun te red in this s tud} were of small size. Most o f the a d e n o m a t o u s and hyperplas t ic polyps were 1 to 3 m m in diameter . Only one a d e n o m a t o u s polyp and five hyperplast ic polyps were larger than 4 ram. No polyps larger than 6 m m were observed within the above-ment ioned categories. An increase in size of adenoma tous polyps with increasing age was not observed in our study. It is also cleat that the me thod used in this s tudy allows for the inclusion o f lesions smaller in size than those usually found in en- doscopy'. The p r e d o m i n a n t small size o f a d e n o m a t o u s polyps is associated in the present study with absence of microscopic signs of epithelial dysplasia.

Figure l is a schematic represen ta t ion o f the dis- t r ibut ion of 179 hyperplast ic polyps accordingly with the ana tomic location in the intestine as de t e rmined by relative distance f rom ICV. Relative distance was riot r ecorded in one polyp. Both sexes were combined because no sex dif ferences were encoun te red in the location of polyps. About half o f the hyperplas t ic polyps are located in the distal colon and rec tum as has been described in o ther populations.-" It is pecul- iar, however, that about 28 per cent of hyperplast ic polyps are located in the r ight colon. Such finding differs f rom the pa t te rn seen in popula t ions with high risk for colonic cancer. 7

Adenomatous polyps for both sexes coenbined are concent ra ted in the right side of the colon with 46 pe t cent o f them located in the cecum and ascending

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T.aBLE 3. Ade.~m.matous and [I~;perplastic Polyps: b 3' ,4ge and 5ex---Medel,.h'n, Colombia (197I-73)

Age G:oup Both (years) Males Females Sexes

44 or under - 1 i 45-54 2 2 4 55-64 4 2 6 65 and over 6 1 7

FoT.,d. 12 6 18

colon (Fig. 2). T h e relative distance f l om ICV was not recorded in two instances so that data on this f igure are on 58 adenoma tous pol?ps. Eight a d e n o m a t o u s polyps (13.8 per cent) were located between 10 and 22 cm f rom the pectinate line and ten more (17.2) were observed at less than 10 cm f rom the same line. In general , this distr ibution follows very closely that de- scribed in Call, and differs f rom the distribution seen in New Orleans ~'r (greater concentra t ion of lesions in u p p e r segments of rec tum and sigrnoid).

T h e relative f requency of adenoma tous polyps by' s egmen t obse rved in this popu la t ion , as ass igned grossly regardless of relative distance, is comparab le to that o f Call, as shown in Table 5. T h e same table, based on 451 histologicaUy conf i rmed cases d u r i n g a 30-year period, reveals a grea ter n u m b e r of cases of rectal cancer in Medellin. Such finding seems to favor the hypothes is suggest ing two d i f fe ren t ep- i d e m i o l o g i c f e a t u r e s fo r co lon ic a n d r e c t a l cancer.e,'-'"

Age-ad jus t ed p r eva l ence rates fo r hyperp las t i c polyps in Medellin are c o m p a r e d in "Fable 6 with

those r epo r t ed in o ther geograph ic locations, r T h e populat ions are r anked in app rox ima te ly decreas ing o r d e r with respect to colorectal cancer f requency. T h e highest prevalence of hyperplast ic polyps is en- coun te red a m o n g Hawai ian-Japanese who also ha~e the h ighes t inc idence o f co lorec ta l cancer ; o the r populat ions like the Japanese , with low risk o f colo- rectal cancer , have very low p reva lence rates for hyperplastic, polyps. Prevalence rates in the two loca- tions studied in Colombia do not corre la te well with the low incidence of colorectal cancer in the country, an observat ion inconsistent with the h;,pothesis as- signing a p remal ignan t role to this part icular type of cotorectal polyp.

] a b l e 7 shows the age-adjusted prevalence rates for adenomatous polyps in the popula t ion o{" Medellin, Colombia, compa red with the o the r popula t ions men- t ioned above, the number s o f cases being the same as shown in Table 6. Figures for Medellin are closely similar to those found in Call and fit ~ell with the popula t ion rankings in the low cancer risk category.

l)iverticular disease was r a the r in f requen t in the series herein r epor t ed with an overall rate o f 3 per cent for both sexes. Seven out of 16 cases show diver- ticulosis associated with polyps but only one of them revealed adenoma tous polyps. Prevalence of diver- ticulosis increases with age in both sexes as has been observed a m o n g other popula t ions . Tab le 8 shows prevalence figures for Medellin and compares them

�9 " 1 9 with figures for Ha~vanan-Japanese, " J a p a n e s e (Akita and *.Iiyagi), ~ and for people in $5.o Paulo. 9 Diver- ticular disease appears to be much r a re r in Medellin than a m o n g Hawai ian-Japanese *'-' and in $5~o Paulo 9 but more f requent than in Japan . T h e low rate o f diverticulosis in this population, fits well with previous

-l'.aBLt 4. Number o/Polyps ira Positive Specimens b..v ,Sex and 7[Et~e ~f Polyp-- ?,ledeil/,'z: Col,)mbia (1971 --73)

Number of Polyps

5 1 '~ 3 4 or more

Axevage Total N umbev N umber

Number of Polyps; of Polyps Persons Person

Adenomato us

Males Females

Hyperplastic

Males Females

Juvenile

Males Females

l0 6 1 3 1 12 0 i 1 0

30 13 3 5 1 33 9 4 0 4

10 0 0 0 0 1 1 0 0 0

43 21 2.05 19 14 1.?,5

90 52 1.7 3 90 50 1.80

10 112) 1.00 3 2 1.50

V:4ume 24 Number t POLYPS IN LOW-RISK CANCER POPULA'FION 3 ~

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I'm. I. Schematic representat ion o[" the anatomic distribution of hyperplastic pol',ps. Both ~exes combined.

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Fro. 9. Schematic representa t ion o f the anatomic distribution of adenomatous pob. ps. Both sexes combined.

observat ions ~'2a indicating that diverticulosis seldom occurs in populat ions at low risk for colorectal cancer .

Discussion

Studies of the prevalence of colonic polyps in well- d e f i n e d p o p u l a t i o n s a re i m p o r t a n l in o r d e r to examine the relat ionship of polyps to cancer. O u r f indings on byperp las t i c polyps in this par t i cu la r communi ty of Medellin, Colombia, at. low risk of colo- rectal cancer , show some in te res t ing d i f f e r e n c e s

when c o m p a r e d with a s tudy of ano the r Colombian populat ion, that of Call. ~ T h e r e is a concent ra t ion of hyperplast ic polyps in the low rec tum as observed in Call, but there is also some concen t r a t i on in the cecum and the ascending colon. This f inding is pecul- iar to this popula t ion and contrasts clearly with the ana tomic dis t r ibut ion o f the same type of polyps a m o n g p o p u l a t i o n s with h igh risk fo r co lorec ta l cancer. T h e low rectal concent ra t ion o f hyperplast ic polyps could be cor re la ted well with the high relative f requency of cancer in the same ana tomic region ob-

"[:~mE 5. Rd4~,tize Freq~zenc3 (per cent) q/Neopla.lms by Assignme~zt to Segment ~ Large BoT~:el.--Cali and 34edell[.,~

Medellin* Call- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Aden~mat• Adenomatous Polyps Carcin,~ma Polyps Carcirmma

Cecum th rough descending 62 24 59 43

Sigmoid -~ 13 20 9 Rectum 15 63 21 48

* Polyps according to segmen.t assigned grossly regardless of relative distance (1971-73). Relative frequency of carcinoma based on 451 cases conf i rmed by h stology in 30-year period, z'~''~*

t Polyps 1967-69; carcinoma, 1962-67 :

D~s. Cul. ~ ReeF. 3 4 RESTREP(_). F'I AL. J:m.-F~b. ~',~S~.

TABLf 6. Jge-Adjusted Precalence Rate oJ" ltypeT~)lastic Polvps in Some Popu.!ation,~ zoiY! Va,~.'ing R#ksjb~ Colorectzl Cano, r r'9

Population

Number of Specimens per Age Group

Colonic Cancer . . . . . . . . . . . . . . . . . . . . . . . . . . Ptevalence I'requency 20-39 40 -59 60 + (Per Cent)

Males

Hawaii-Japanese New Orleans whites New Orleans blacks Japan (.Akita) Silo Paulo whites $5.o Paulo blacks .Japan (Miyagi) Colombia (Call) Colombia (Medellin)

Females

Hawaii-Japanese New Orleans whites New Orleans blacks Japan (Akita) SS.o F'aulo whites SS.o Paulo blacks Japan (Miyagi) Colombia (Call) Colombia (Medellin)

Very High 2 26 95 73 High 18 67 -t5 15 t tigh 2 l 6:5 132 1 -t Intermediate 24 52 93 2 Intermediate 55 67 79 29 Intermediate 47 44 27 18 I . o w 127 184 185 3

Low 241 258 198 11 Low 116 69 a~'~ 23

Very ttigh 1 7 68 51 High 0 20 23 21 High 18 59 101 8 Intermediate 8 40 62 4 Intermediate 66 59 70 25 I n termediate 50 61 58. 16 Low 78 116 127 1 Low 142 96 79 7 Low 82 56 34 29

"I'ABL~: 7. Age-ddjust, ed Prevalence Rate of Adenomatous Pol~p,g in Populatior~s with Varying Rt~ks flor Co&rectal Cancer

Colonic Cancer Prevalence Population Frequency (Per Cent)

Males

Hawaii-japanese Very High 63 New Orleans blacks High 37 New Orleans wMtes High 36 Japan (Akita) Intermediate 36 $5.o Paulo w h i t e s Intermediate 20 S~o Paulo b l a c k s Intermediate 1 t Japan (Miyagi) Low 14 Colombia (Medellin) I.ow 14 Colombia (Call) Low 11

Females Hawaii-japanese Very High 52 New Orleans blacks High 29 New Orleans whites High 20 Japan (Akita) Intermediate 20 Silo Pauto w h i t e s Intermediate 17 $5o Paulo b l a c k s Intermediate 13 japan (Miyagi) Lo~ 12 Colombia (Medellin) I.ow 11 Colombia (Call) l,ow 11

served in a 30-year pe r iod in this p o p u l a t i o n . Right- s ided cokmk: cancer , however , is no t as f r e q u e n t l y seen as hyperp las t i c polyps in the cecum a n d ascend- ing colon. T h e p reva lence rates of hyperp las t i c polyps are g rea t e r in Medel l in t h a n in Call in bo th sexes, the re be ing a h i g h e r overal l p r eva l ence in w o m e n than in men . A progress ive increase in p r eva l ence rates with age for s ingle a n d m u h i p l e hyperp las t i c polyps is seen in this p o p u l a t i o n as it has b e e n ob- served in o t h e r series. A c o m p a r i s o n of p r eva l ence ra tes a m o n g p o p u l a t i o n s with d i f f e r e n t levels o f

cance r risk reveals incons i s tenc ies in associat ion with hyperp las t i c polyps. All f i n d i n g s r e g a r d i n g h y p e r -

plastic polyps in this r e p o r t ind ica te tha t the re is no good e p i d e m i o l o g i c e v i d e n c e to c o n s i d e r t h e m as p r e m a l i g n a n t lesions, c o n f i r m i n g o b s e r v a t i o n s m a d e by' o t he r inves t iga tors o n this par t i cu la r subject . 8":

T h e low p reva l ence of a d e n o m a t o u s polyps in this

p o p u l a t i o n corre la tes well wi th in the low risk o f colo- rectal cancer , as it does in o t he r low-risk p o p u l a -

tions. Males in Medel l in show slightly g r e a t e r preva- l e nc e rates t han in Call b u t the rates are very close in females in bo th p o p u l a t i o n s . Rates increase with in- c reas ing age both for s ingle a n d mul t ip le a d e n o m a t - ous polyps in males a n d females . T h e a n a t o m i c dis-

V o l u m t 2, i ~;~:,nb,:, ! POI_YPS IN I_OW-RISK CANCH~. P O P U I . A ' I I O N 3 D

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tr ibution of adenomatous polyps is also similar to that seen in Caii, with grea ter concentra t ion of polyps in segments p rox ima l to the r ec tos igmoid j u n c t i o n (0-79 per cent relative distance f rom ICV). Only eight o t 62 adenomatous polyps (13 per cent) were found in the upper rec tum and sigmoid, a n u m b e r also comparable to that fourtd in Cali and 1.3 times lower than the co r respond ing figure for New Or- leans, r Othe r findings regard ing adenolnatous polyps in this populat ion are correlated with the low risk to t colorectal cancel-. A h h o u g h the polyps do not in- crease in size with age, as observed in Cali, they are usuallv smaller than those found in New Orleans and other high-risk populations, r'~e They also have a lack of villous changes and epithelial dysplasias, features which have been implicated in the lnalignant trans- f()rtnation . ',4. process. 2a O u r observations concern ing this p , t r t icular type o f po lyp go a long with the hypothesis that they are premal ignant lesions, accord- ing to the epidelniologic model proposed by Haenszel and Correa. ~a'*4 Th e high f requency of low rectal cancer in our popula t ion seems to indicate that a greater number of adenomatons polyps located irl the low rectum become lnalignant, as has been suggested by o t h e r s . ~ ' ~

Juvenile polyps were not a p rominent [inding in the present s~ucly because we purpose ly exc luded c h i l d r e n below the age o f 10 years f r o m o u r collection.

Tile low prevalence rates of divevticular disease found in our populat ions contrast greatly with that found in populat ions with high risk for colorectal cancer? 2 Burkitt ~ has p roposed an association be- tween diverticulosis of the colon, adenonta tous polyps and carcinoma based upon observations in Africa. t tis observations seem to be suppor ted by findings made by other investigators 9' v,.2a and by our findings.

A c k n o w l e d g m e n t s

T h e technical assistance o f Mrs. Raquel Restrepo de Sierra and of Mr. "l['ito Co[lazos is acknowledged. O u r thanks tu Drs. Casar A. Giratdo and David SucscmL from the Medico Legal Service in Medellin. tor ct~operating in the collection o f specimens . We are also greatful to Mrs. Ada C'lausing for assistance ii~ p repa r ing the manuscr ip t .

R e f e r e n c e s

I. B u r k i t t DP. R e l a t e d d i s e a s e - - - r e l a r e d c a u s e } L a n c e t 1969;2:1229-31.

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M e m o i r

S:,~nH, R o z r R r S~_~w, W a s h i n g t o n , D.C.; b o r n .July 26, 1915 in Og- den , U tah : g r a d u a t e o f G e o r g e W a s h i n g t o n Univers i ty , I943: with p o s t g r a d u a t e surgical t r a i n i n g at S u b u r b a n Hospi ta l in Be thesda , Mary- land, a n d at Mayo Clinic in Roches te r , Minneso ta . Dr. Stnitl'l r ece ived his colon a n d rectal t r a i n i n g u n d e r De. G a r n e t W. Ault , W a s h i n g t o n , D.C.

Dr. Smi th j o i n e d ~he A m e r i c a n Society o f Colon a n d Rectal S u r g e o n s in 1952 a n d was e levated to Fel lowship in 1968. t i e was a D ip loma te o f the A m e r i c a n B o a r d o f Colon a n d Rectal Su rge ry a n d a Fellow o f the A m e r i c a n Col lege o f S u r g e o n s : a m e m b e r o [ the A m e r i c a n Medical Associat ion, W a s h i n g t o n Medical a n d Surgical Society. the Pan A m e r i - can Medical Society, G e o r g e W a s h i n g t o n Univers i ty Medical Society, Ph i l ade lph i a Proctologic Society, W a s h i n g t o n A c a d e m y of Su rge ry , a n d I..ouis Mackall Medical Society. Pr io r to his r e t i r e m e n t in 1978, he was on the staffs o f Doctors. W a s h i n g t o n Hosp i ta l Cen te r , C h i l d r e n s , a n d Co lun tb ia Hospi ta ls in W a s h i n g t o n , D.C. Dr. Smi th d ied D e c e m b e r 22, 1979.