Pad´e quantification of malignant and benign ovarian MRS data - Signal Processing in MRS with Biomedical Applications - page 277

9
Pade quantification of malignant and benign
ovarian MRS data
Ovarian cancer is estimated to be the seventh leading cause of death from can
cer among women worldwide [311]. It is the most common cause of death from
gynecological cancer in many developed countries and has the highest mortal
ity rate of all gynecological cancers [312, 313]. Despite progress in treatment,
mortality rates from ovarian cancer have not substantially improved over the
last 30 years [314]. This is due mainly to late detection after the disease has
spread beyond the true pelvis, since when confined within the ovary (stage
Ia) the 5year survival rate is well over 90% [315]-[317]. Survival, therefore,
depends upon early detection of ovarian cancer.
However, this is still beyond current reach with standard diagnostic meth
ods [7, 318]. For example, although useful for following patients with estab
lished ovarian cancer, the tumor marker CA125 1 does not yield improved
early detection when used alone [318]-[320]. Some recent studies have sug
gested certain genomic and proteomic patterns as possible complementary
biomarkers for early ovarian cancer [321]-[323]. However, more investigation
is certainly needed to determine whether these provide enough improvement
in sensitivity and specificity to support their routine use for ovarian cancer
screening [313, 315].
Transvaginal ultrasound (TVUS) is sensitive but not su ciently specific
to distinguish benign from malignant adnexal lesions. The high rate of false
positive findings with TVUS leads to many surgical procedures that do not
detect any cancer [315, 318].
Largescale trials are ongoing to determine whether the combination of
TVUS plus CA125 could provide acceptable levels of diagnostic accuracy
for ovarian cancer screening. Unfortunately, however, this does not appear
to be the case [314]. In the Prostate, Lung, Colorectal and Ovarian (PLCO)
Trial in which approximately 40000 women participate, the positive predictive
value of abnormal TVUS plus CA125 was very low: 23.5%. Thus, to find 26
cases of ovarian cancer (plus 3 other cancers), 535 women underwent surgical
procedures [324].
1 CA-125 is a protein whose presence is often associated with ovarian cancer. However, it
has poor sensitivity for early stage malignancy and is also non-specific, being present in
other cancers, as well as several non-malignant conditions, including pregnancy.
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