Case Control Study

Slide 1: 

USE OF HAND HELD CELL-PHONE AND PRIMARY BRAIN CANCER – A CASE CONTROL STUDY MUNAWAR KHAN ,IIHMR JAIPUR

BACKGROUND-13 country Inter phone study : 

BACKGROUND-13 country Inter phone study Done by- International Agency for Research on Cancer (IARC) Primary Objective- To assess whether RF energy exposure from cell phones is associated with an increased risk of malignant or benign brain tumors and other head and neck tumors Participating Countries- Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden, and the United Kingdom Conclusion- No clear cut increase in risk of brain cancer for cell phone users but the results were less than conclusive.

OTHER STUDIES : 

OTHER STUDIES In addition, pooled analyses of data from four Nordic countries and the United Kingdom did not show overall associations between the risk of Glioma or Meningioma and the cumulative hours of cell phone use or the number of calls. But there was a slightly increased risk of Glioma occurring on the same side of the head as the reported phone use among persons who used a cell phone for at least 10 years .

FLAWS IN THE PREVIOUS STUDIES : 

FLAWS IN THE PREVIOUS STUDIES Selection Bias Definition of “Regular” Cellphone User Exclusion of Young Adults and Children from the Interphone Study Brain Tumor Risk from Cellphones Radiating Higher Power in Rural Areas Were Not Investigated Exclusion of Brain Tumor Types Exclusion of Brain Tumor Cases Because of Death or Too Ill to Respond Recall Accuracy of Cellphone Use Funding Bias

Justification : 

Justification India’s mobile market is fastest growing in the world and according to reports India will overtake China to become the world’s largest mobile market by the year 2013. Total no. of telephones in the country crossed the 600 million mark in Feb. 2010. The overall teledensity will shoot up to 75% of the total population by 2013. Cell phones emit radiofrequency (RF) energy (Radio waves) which are a form of radiation. No studies have been carried out in India previously.

RATIONALE OF STUDY : 

RATIONALE OF STUDY Industry’s own research showed Cell-phones caused brain tumors. Subsequent industry-funded research also showed that using a Cell-phone elevated the risk of brain tumors. Despite the systemic-protective-skewing of all results in the Interphone studies, significant risk for brain tumors from Cell-phone use was still found. There have been numerous governmental warnings about children’s use of Cell-phones. Exposure limits for Cell-phones are based only on the danger from heating.

Slide 7: 

Cell-phone radiation damages DNA, an undisputed cause of cancer. Cell-phone radiation has been shown to cause the blood-brain barrier to leak. Cell-phone user manuals warn customers to keep the cell-phone away from the body even when the Cell-phone is not in use. Federal Communications Commission (FCC) warning for cordless phones.

PROBLEM DEFINITION : 

PROBLEM DEFINITION Brain cancer incidence and mortality (death) rates have changed little in the past decade. 22,070 new diagnoses and 12,920 deaths from brain cancer were estimated for 2009.  The 5-year survival rate for brain cancers diagnosed from 1999 to 2006 was 36.3 percent . The risk of developing brain cancer increases with age. Incidence rate from 2003 to 2007 for people under age 65 was 4.6 for every 100,000 persons compared with 19.4 for every 100,000 persons age 65 and above.

Objectives : 

Objectives To determine the rate of incidence of primary brain tumor in handheld cellular phone users To estimate the frequency of exposure that increases the risk

Research Question & Hypothesis : 

Research Question & Hypothesis HYPOTHESIS:- Use of handheld cellular phones increases the risk of developing primary brain tumors. RESEARCH QUESTION:- Whether the use of handheld cell phone increases the risk of Primary Brain cancer and if so is it related to pattern of use of cell phones?

Biological Plausibility : 

Biological Plausibility Microwave radiation Thermal Heating of brain   Symptoms (Headaches, Fatigue, tissue swelling, tingling and other severe potential long-term damages)

METHODOLOGY : 

METHODOLOGY STUDY BASE Multicentric study Conducted across cancer hospitals in metropolitan cities of India

Selection Criteria for Cases : 

Selection Criteria for Cases Inclusion Criteria:- Patients of primary brain tumor In the age group of 18-60 yrs Selected from the cancer hospitals Diagnostic Criteria- MRI and Biopsy Exclusion Criteria:- Metastatic cases of brain tumor

Controls : 

Controls Inclusion Criteria- Patient of carcinoma other than brain tumor Selected from the same hospitals Same time period Same age group(18-60 years) Exclusion Criteria – Any other carcinomas which are caused by RF waves

Sample Size : 

Sample Size Cases - 299 Controls - 897 Total sample size- 1196 Sample size was calculated considering : Confidence interval- 95% Power - 80% Control : Case Ratio - 3:1 Odds Ratio - 20.39

Exposure : 

Exposure Use of mobile phones since 5 years before the date of diagnosis. Categories of usage:- < 1hour/day 1-2 hrs/day 2-3 hrs/day 3-4 hrs/day > 4hrs/day

Factors affecting Exposure : 

Factors affecting Exposure The number and duration of calls. The amount of cell phone traffic at a given time. The distance from the nearest cellular base station. The quality of the cellular transmission. The size of the handset. Whether or not a hands-free device is used.

Data collection tools & techniques : 

Data collection tools & techniques A structured questionnaire would be used to ascertain the average usage of cell phone per day during the last 5 years.

Validity issues : 

Validity issues Internal Validity Biases- 1) Recall bias 2) Information bias 3) Selection bias Confounding factors- 1) Occupation (Frequent exposure to electro magnetic waves) 2) Sex 3) Age

Adjustment : 

Adjustment To reduce selection bias- We selected tumor patients from the same hospital, in same age group, and for the same time period. To reduce Information Bias- Cases and controls both were selected from the diagnosed cancer patients, and hence the possibility of differential response was reduced. Issues of recall bias- May be there, because of long recall period of 5 years. For confounders -Multivariate logistic regression analysis can be done to reduce the effect of confounding variables.

Generalizability : 

Generalizability Impact of exposure is same in all mobile phone users irrespective of age, sex etc. Radio-energy waves would act by the same mechanism to cause brain tumor irrespective of age, sex and place. All cases of carcinomas are referred to the tertiary hospitals for treatment irrespective of the place of residence.

Slide 22: 

“Exposure to cell-phone radiation is the largest human health experiment ever undertaken, without informed consent, and has some 4 billion participants enrolled. Science has shown increased risk of brain tumors from use of Cell-phones, as well as increased risk of eye cancer, salivary gland tumors, testicular cancer, non-Hodgkin's lymphoma and leukemia. “ The public must be informed