"Long before it's in the papers"
February 09, 2011

RETURN TO THE WORLD SCIENCE HOME PAGE

Prostate cancer joins growing list of cancers dogs could sniff out

Feb. 9, 2011
Courtesy of Elsevier Press
and World Science staff

Trained dogs can de­tect pros­tate can­cer by sniff­ing pa­tients’ urine, sci­en­tists have found.

Sci­en­tists are in­creas­ingly in­ter­est­ed in the abil­ity of man’s best friend to catch the scent of chem­i­cals that give away the pres­ence of can­cers in early stages, when they are more easily cur­a­ble. Past stud­ies have have re­ported on ca­ni­nes’ abil­ity to sniff out lung and breast can­cers.

The new stu­dy, by Jean-Nicolas Cor­nu of Ten­on Hos­pi­tal in Par­is and col­leagues, fol­lowed up on pro­pos­als that in­gre­di­ents of urine known as vol­a­tile or­gan­ic com­pounds may serve as signs of pros­tate can­cer—the third most com­mon cause of cancer deaths in men, ac­cord­ing to the U.S. Na­tional In­sti­tutes of Health. The di­sease be­gins in the pro­state gland, a wal­nut-sized or­gan next to the ure­thra, the tube that passes urine out of the body.

Cor­nu and colleagues trained a Bel­gian Ma­li­nois shep­herd dog over 24 months to smell and rec­og­nize urine of peo­ple with pros­tate can­cer. To stand­ard­ize urine sam­ples for the stu­dy, all sam­ples were fro­zen for pre­serva­t­ion and heat­ed to the same tem­per­a­ture. 

The dog’s abil­ity to dis­crim­i­nate urine from peo­ple with and with­out pros­tate can­cer was as­sessed in a dou­ble-blind test, re­search­ers said, in which the ex­pe­ri­menters them­selves weren’t told which sam­ples were which. 

The urine came from 66 pa­tients re­ferred to an urol­o­gist for show­ing warn­ing signs of pros­tate can­cer. Only half of the pa­tients turned out to ac­tu­ally have the ill­ness based on a bi­op­sy, while the oth­er half did not.

The dog nosed out the sam­ples and cor­rectly rec­og­nized the can­cer sam­ples in 30 of 33 cases, the in­ves­ti­ga­tors said, re­port­ing their find­ings in the Feb­ru­ary is­sue of the jour­nal Eu­ro­pe­an Urol­o­gy. One of the pa­tients that the pooch “incor­rectly” pegged as a can­cer case, they not­ed, did in fact turn out to have can­cer based on a sec­ond bi­op­sy.

The spe­cif­ic com­pounds giv­ing off the tell-tale scent haven’t yet been de­fin­i­tively iden­ti­fied, the re­search­ers not­ed, but the ca­nine re­search could help to clar­i­fy this ques­tion and help de­vel­op yet ad­di­tion­al screen­ing tools.

* * *

Trained dogs can detect prostate cancer by sniffing patients’ urine, scientists have found. Scientists are increasingly interested in the ability of man’s best friend to catch the scent of chemicals that give away the presence of cancers in early stages, when they are more easily curable. Past studies have have reported on canines’ ability to sniff out lung and breast cancers. The new study, by Jean-Nicolas Cornu of Tenon Hospital in Paris and colleagues, followed up on proposals that ingredients of urine known as volatile organic compounds may serve as signs of prostate cancer. The researchers trained a Belgian Malinois shepherd dog over 24 months to smell and recognize urine of people with prostate cancer. To standardize urine samples for the study, all samples were frozen for preservation and heated to the same temperature for the sniff tests. The dog’s ability to discriminate urine from people with and without prostate cancer was assessed in a double-blind test, researchers said, in which the experimenters themselves weren’t told which samples were which. The urine came from 66 patients referred to an urologist for showing warning signs of prostate cancer. Only half of the patients turned out to actually have the illness based on a biopsy, while the other half did not. The dog nosed out the samples and correctly recognized the cancer samples in 30 of 33 cases, the investigators said, reporting their findings in the February issue of the journal European Urology. One of the patients that the pooch “incorrectly” pegged as a cancer case, they noted, did in fact turn out to have cancer based on a second biopsy. The specific compounds giving off the tell-tale scent haven’t yet been definitively identified, the researchers noted, but the canine research could help to clarify this question and help develop yet additional screening tools for prostate cancers.