7/31/2019 Doena+cistica+adquirida
1/2
5. Wong G, et al.: Cost-effectiveness of breast cancer screening
in women ondialysis. Am J Kidney Dis52:916929,2008
6. LeBrun CL, et al.: Life expectancy benefits of cancer
screening in theend-stagerenal diseasepopulation. Am J Kidney Dis
35:237243, 2000
7. Cohen LM, et al.: Predicting six-month mortality for patients
who are onmaintenancehemodialysis. ClinJ Am SocNephrol5:7279,
2010
Should screening for acquired cysticdisease and renal malignancy
beundertaken in dialysis patients?
Swathi SinganamalaandUrsula C. Brewster
Acquired cystic kidney disease (ACKD) is a commonand worrisome
complication of end-stage renal disease(ESRD) and was first
described in 1977. Diagnostic cri-teria consist of the presence of
four or more cysts in eachkidney without a family history of cystic
kidney disease.Patients with severe disease can have more than
ninecysts in each kidney and cysts larger than 5 cm with little
remaining non-cystic renal parenchyma. ACKD is usu-ally
asymptomatic but can be complicated by pain,spontaneous hemorrhage
and renal cell carcinoma(RCC). Spontaneous hemorrhage, exacerbated
by hepa-rin use and platelet dysfunction, can be severe and
causesudden hypotension during hemodialysis (1).
Prevalence of ACKD is primarily a function of timeon dialysis;
however up to 10% of patients withadvanced CKD not yet on dialysis
have ACKD. After3 years on dialysis nearly half of ESRD patients
haveACKD, and this number increases to 90-100% at10 years (2). The
etiology of ESRD does not seem toinfluence the occurrence of ACKD,
although there is
slight preponderance in older men and there is no majorracial
difference (2,3). Dialysis duration is the only factorthat affects
the severity of ACKD. Age, dialysis ade-quacy, residual renal
function does not appear to affectthe severity of cystic disease
(4). Although some report alower risk in patients on peritoneal
dialysis, this is notconsistent across the literature (5).
Renal cell carcinoma is a well-recognized complica-tion of ACKD.
The incidence of RCC in ESRDpatients is 14% (6,7). It is
predominantly unilateralbut may be bilateral in 2530% of cases
(8,9). Twomajor histological types have been described: clear
celland papillary type. Although papillary RCC is morecommon in
ESRD patients than in the general popula-
tion (30% versus 1015% respectively), clear cell is themost
common type (5,9). Because of the increased riskof RCC in patients
with ACKD, the overall prevalenceof RCC is about 3035 fold higher
in dialysis patientscompared to general population.(5). RCC is
accompa-nied by ACKD in about 7580% of the cases (7,8).Cysts >3
cm in diameter have a higher risk of malig-nancy (3). Duration on
dialysis is again the most impor-tant risk factor for the
development of malignancy
(8,10). The published mortality for patients undergoingradical
nephrectomy for RCC without metastasisranges from 0.5 to 6% and is
up to 10% with meta-static disease (11).
Screening for ACKD might make sense intellectually,but its cost
effectiveness in the ESRD population, withits associated
comorbidities, must be carefully consid-
ered. It is important to remember that the median age ofpatients
starting dialysis is increasing and the USRDSdata cites median 5
year survival of incident ESRDpatient as only 38%.
Decision analysis has been used to evaluate the bene-fits of
screening by performing either ultrasound (US)or computed
tomography (CT) every 3 years and thenannually in patients with
ACKD in a recent study (12).Baseline analysis showed that both CT
and USdecrease the cancer deaths by half for those ESRDpatients
with a life expectancy of 25 years or more.Screening in these
patients increased life expectancy by1.6 years (12). However, a 25
year life expectancy is
uncommon in the average dialysis unit. Another studyused
mathematical modeling to show a 35% reductionin risk of death, with
survival benefit of 3.3 years, fromall causes after adjustment for
age, duration of dialysisand other comorbid illnesses with a
screening by CT orUS (11).
We cannot extrapolate these data to all patients, asmost 64
year-old dialysis patients do not have 25-yearlife expectancy. Add
to that, the 5 year survival of anESRD patient with RCC stage 1 is
35%, which is similarto an ESRD patient without RCC. ESRD patients
withRCC are more likely to die of cardiovascular diseaserather than
the RCC (2). The largest beneficial effect inboth the studies was
seen in young patients who might
be future transplant recipients.How about transplant patients? A
recent review of
1000 transplant recipients followed for 28 years showedthat ACKD
is less common in transplant recipientscompared to ESRD patients as
a whole (23% versus80%), but the prevalence of RCC was higher (19%
ver-sus 0.5%) in recipients with than without ACKD (13).The Bosniak
scoring system (Table 1) categorizes cysticlesions, and is
recommended as an excellent tool forrisk stratification in
patients. Most recommend yearlyultrasound screening after
transplant for all irrespectiveof ACKD (13). Once ACKD develops,
ultrasoundshould be done more frequently; every 6 months for
Seminars in DialysisVol 24, No 4 (JulyAugust) 2011pp. 365366DOI:
10.1111/j.1525-139X.2011.00908.x 2011 Wiley Periodicals, Inc.
SCREENING FOR ACQUIRED CYSTIC DISEASE AND RENAL MALIGNANCY
365
