PART THREE
Special Techniques in Cytology
T a b le 3 6 .4 C om parison o f th e C linical and Laboratory Value o f th e S eco nd -g en e ra tion H ybrid C apture Assay and Polym erase C hain R eaction T e chniques“
C h a ra c te ris tic
H C2 assay
P o ly m e ra s e c h a in re a c tio n
FD A -approved fo r prim a ry a d ju n ctive screening in
w o m e n 30 years and o ld e r
Yes
No
R eim bursem ent
Established
Variable
FD A -approved fo r ASCUS reflex te stin g
Yes
No
FD A -approved fo r te stin g fro m liq u id c y to lo g y
specim ens
Yes
No
C linical perfo rm a n ce
> 96% clinical sensitivity,
> 99% negative p red ictive value
D eterm in e d by ind ivid u a l laboratory
validations
S tandardized m e th o d
Yes
Yesb
Sam ple p rep aration
N ot required
N eeded to rem ove in h ib itors
Laboratory re qu irem ents
Requires single w o rk area
Requires m u ltip le w o rk areas w ith strict,
u n id ire ctio n a l w o rk flo w
T h ro u g h p u t
Processes u p to 176 tests in 5.5 h
D epends o n m e th o d “
Data used to su p p o rt ACOG, ACS, and ASCCP
guidelines
Yes
No
H igh risk-typ e panel
H um an pap illo m a viru s typ e s 16, 18, 3 1,33, 35, 39, 45, 51,52,
56, 58, 59, 68
D epends o n m e th o d “
Low risk-typ e panel
H um an pap illo m a viru s typ e s 6, 1 1 ,4 2 -4 4
D epends o n m e th o d “
D etectio n if L1 g e n e is d ele te d
Yes
N o (if consensus prim ers are used)
Reports o b je ctive results
Yes
Yes
P erform ance o p tim ize d fo r risk assessm ent and
e ffe ctive screening program s
Yes
N o“
A b u n d a n t s u p p o rtin g data
Yes
Yes
S im ple tra in in g and user va lid a tion
Yes
Y es/N of
Q uality co ntro ls p rovid e d
Yes
R igorous in-house co ntro ls required
Test fo r sexually tra n s m itte d infections fro m th e
sam e specim en
Yes
No
ACOG, American College of Obstetricians and Gynecologists; ACS, American Cancer Society; ASCCP, American Society for Colposcopy and Cervical Pathology; ASCUS,
atypical squamous cells of undetermined significance; FDA, US Food and Drug Administration; PCR, polymerase chain reaction.
^Modified by the authors from data presented on the website of Digene Corp. (http://www.digene.com).
Standardized PCR-based techniques available on the market.
Throughput is highly variable, and no direct comparisons with existing PCR-based techniques available as yet.
dNNO LiPA detects 25 genotypes, Roche Amplicor 13, Linear Array 37, Luminex xMAP 26, and, for example, EasyChip detects 42 genotypes.
eData on new commercial PCR assays emerging.
fPCR-based techniques generally more laborious to learn; situation may change with the novel commercial assays.
com parison w ith any single PCR assay is u nfa ir, however, because
th is new D igene assay com bines tw o tests, one w ith h ig h sensi-
tiv ity (H C 2 ) and one w ith hig h specificity (P ap anicolaou), and
due to th is in h e re n t technical design it is h ig h ly u n lik e ly th a t
any single PCR (o r o the r) assay can com pete in perform ance
w ith the D N A w ith Pap test. M o st im p o rta n tly, c om b in in g H C 2
and Papanicolaou sig n ific an tly im proves the PPV o f the test,
w h ic h is the single m ost im p o rta n t test perform ance ind ica to r
in a screening setting, as em phasized fo r exam ple in the In te r-
n a tio n a l Agency fo r Research o n Cancer's cancer ep id em iolog y
textbooks.78
FISH in Gynecologic Cytology
In te g ra tion o f H P V in to the h ost genom e and gain in copy
n um b er o f the oncogenes coding fo r the R N A c om p onent o f
telom erase (TERC) at 3q26 and M Y C at 8q24 have recently
been show n to be critical fo r th e developm ent and progression
o f u terine cervical cancer. The prevalence o f H P V inte g ratio n and
the copy n um b er o f these tw o genes increase w ith the severity
o f dysplasia up to invasive carcinom a.79,80 In te g ra tion o f vira l
D N A in to the h ost D N A is considered a key event fo r the p ro -
gression o f cervical neoplasia.81,82 H P V inte g ratio n is believed to
drive tra n s fo rm a tio n b y d isrup ting several genes and pathways.
A m u ltita rg e t FISH assay w ith probes against h ig h -risk H P V
D N A , M YC , and TERC has recently been developed fo r a p p li-
cation in gynecologic cytology (A b b ott M olec ular Inc.). This
cocktail o f FISH probes allow s the id e n tific a tio n o f H P V-positive
cells to d eterm ine w h e th e r H P V D N A is episom al o r integrated
in to the h ost genome, as w e ll as the e nu m e ration o f the num b er
o f gene copies o f TERC and M Y C in these cells (Figs 36.12 and
36.1 3 ) . T his m olec ular genetic in fo rm a tio n m ig h t help to better
define th e risk o f progression in in d ivid u a l patients. Cells w ith
H P V inte g ratio n (d o t-like signals) and sim u lta n e o u sly increased
1086
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