Methodology:
The researchers will analyze the accuracy of two diagnostic procedures namely Core Biopsy and Fine
needle aspiration biopsy (FNAB). A tally of patients who had undergone either FNAB or Core Biopsy for
the last 2007-2008 will be gathered by reviewing the medical records from University of Santo Tomas
Hospital medical records. After getting the sample population, the researchers will exclude patients who
had not undergone surgical resection. The sample population will then be subdivided into two groups
namely: patients who undergone Fine needle biopsy and those who had Core needle biopsy prior to
surgical resection as diagnostic procedure. Histopathology results of biopsy after surgical resection, and
either fine needle biopsy or core needle biopsy will be obtained from a review of medical records and
will be statistically analyzed as to its sensitivity and specificity. Histopathology results of biopsy after
surgical resection will be used as the gold standard.
Patients undergone
FNAB or Core Biopsy
2007-2008
Excluded
Did not undergone
surgical resection
Undergone surgical
resection
FNAB
Core Biopsy
Statistical Analysis
Inclusion Criteria:
1. Patient who had Core needle Biopsy or Fine needle Aspiration Biopsy.
2. Patient who had undergone surgical resection after undergoing Core needle biopsy or fine
needle biopsy.
Exclusion Criteria:
1. Patients who have undergone other therapeutic procedures prior to surgical resection.
2. Patients who have undergone other surgical procedures prior to resection.
Sample size calculation
Sample Size for Cross-Sectional, Cohort, & Randomized Clinical Trial Studies
Two-sided significance level(1-alpha):
Power(1-beta, % chance of detecting):
95
80
Ratio of sample size, Unexposed/Exposed:
Percent of Unexposed with Outcome:
Percent of Exposed with Outcome:
Odds Ratio:
Risk/Prevalence Ratio:
Risk/Prevalence difference:
1
90
76
0.34
0.84
-14
Kelsey
Fleiss
Fleiss with CC
Sample Size - Exposed
Sample SizeNonexposed
109
108
121
109
108
121
Total sample size:
218
216
242
References
Kelsey et al., Methods in Observational Epidemiology 2nd Edition, Table 12-15
Fleiss, Statistical Methods for Rates and Proportions, formulas 3.18 &3.19
CC = continuity correction
Results are rounded up to the nearest integer.
Reference:
A Prospective Study of the Use of Fine-Needle Aspiration Cytology and Core Biopsy in the Diagnosis of
Breast Cancer (G. Dennison, FRCS, R. Anand, FRCS, S. H. Makar, FRCS, and J. A. Pain, FRCS Department of
General Surgery, Poole Hospital, Poole, United Kingdom)
“Of the 105 patients with malignancy, confirmation was made in 95 by fine-needle aspiration cytology
(FNAC) with a sensitivity of 90.4% and 100 by core biopsy with a sensitivity of 95.2%. The sensitivity of
core biopsies increased with the number of cores taken (one core, 76.2%; two cores, 80.9%, three cores,
89.2%; four cores, 95.2%)”
Statistical analysis:
Data gathered will be analyzed based on sensitivity and specificity. For sensitivity analysis, true
positive is defined as patients having same positive biopsy findings before and after surgical resection.
False negative is defined as patients having negative diagnostic findings and positive surgical resection
biopsy findings. For specificity analysis, true negative is defined as patients who had negative findings on
the diagnostic procedure. False positive is defined as patients who had positive findings on the
diagnostic procedure and a negative finding on surgical resection biopsy.
The following formulas will be used to determine:
Sensitivity = TP / (TP + FN)
Specificity = TN / (TN + FP)
Dummy Tables
Histopathology
Positive
FNAB
Positive
Negative
Histopathology
Positive
Negative
Core Positive
Biopsy Negative
Negative