Hi,
1.
The exposure categories are:
a. Use of talcum powder (if ever used or used in the last year or at the ages of 10 to 13 years)
b. Place of use (perineal [private] area, underwear, diaphragm, cervical cap, directly to the vaginal area or on sanitary napkins)
c. Time since use (<1 year, 1-<10 years, 10-<20 years, 20-<30 years, 30+ years)
d. Frequency of use (no, <1/week, 1-6 times/week, daily)
The outcome categories are:
a. Self- report of recent cancer diagnoses (i.e. tumors originating in the ovary, peritoneum, and fallopian tubes as ovarian cancers). Confirmed for diagnosis and disease details using patient's medical records.
b. National Death Index searches (among deceased participants)
Null hypothesis: There is association between use of powder in the genital area and risk of ovarian cancer.
2.
a. Advantage of cohort study over RCT: Since talcum powder (product under study) is suspected (known) to cause carcinoma, it cannot be given to participants in RCT. Hence it would be unethical to conduct this kind of experiment.
b. Advantage of cohort study over cross-sectional (CS) study: CS study will not give the temporal relation, i.e. if talc is causing cancer or it is just that proportion of respondents using talc have higher incidence of cancer. we can not establish causal relationship here.
c. Advantage of cohort study over case-control (CC) study: Since we will recruit patients with cancer in this study design, these patients may remember use of talc more distinctly than those who have no cancer. This can introduce recall bias in our study.
3.
a. There is no actual increased risk.
b. Small sample size of study (not applicable in this study)
c. Presence of bias (selection/information)
d. Study population is not representative of target population (healthy, educated women were selected in this study)
e. Random error
f. Inadequate follow-up period (certain cancers take long time to develop)
g. Not adjusting for confounders that dilutes the effect.
h. Unknown confounders
4.
a. Temporality: With this cohort study we can prove that use of talcum powder precedes cancer.
Need more studies to prove the following:
b. If we can prove that if talc use is removed, then incidence of cancer is decreased
c. Predictive performance: Since this talcum is also used by babies (female), if we get increased risk of cancer in babies, we can prove the causal relationship.
c. Consistency: If similar association is reported from different studies, or different geographies, such as from Asia or Africa etc or in different group of women.
d. Dose-response relationship: Those women who use talc more frequently are associated with increase in incidence of cancer than those who use it infrequently.
e. Biological plausibility: If we can prove in lab that the powder has ingredients that can alter genetic material to predispose to cause cancer.
