FRIDAY October 19, 2007 (Foodconsumer.org) -- Use of antibiotic may increase risk of developing breast cancer in a dose-dependent manner, according to a study published in the October 8, 2007 of Pharmacoepidemiology and Drug Safety.

The study led by researchers from King Saud bin Abdulaziz University for Health Sciences in Riyadh, Saudi Arabia showed use of antibiotics increased risk of breast cancer by 50 to 79 percent, depending upon the number of prescriptions an individual received during one to 15 years prior to the diagnosis of the disease.

The case-control study was based on 3099 cases of breast cancer and 12,396 matched controls that enrolled in the Saskatchewan Prescription Drug Plan ( Canada) between the years 1981 and 2000.

In the study, M. Tamim H and colleagues did not find the timing of antibiotic use had any effect on the breast cancer risk though.  

Use of classified antibiotics was also linked to the risk of breast cancer and the risk was also linked with the units of antibiotics used, according to the study.

The researchers concluded a dose-dependent increase in breast cancer risk was associated with antibiotic exposure up to 15 years in the past.

But they said the results did not suggest that use of antibiotics caused breast cancer because of lack of temporal trends and the absence of class-specific effects.

This is not the first study that linked use of antibiotics with increased risk of breast cancer.   Some early studies have already suggested that antibiotic use may raise the risk.

A scientist affiliated with foodconsumer.org suggested that a causal relationship may not be ruled out by this study per se.

Use of antibiotics eliminates all beneficial bacterial floras in the body and creates an environment for opportunistic yeasts and molds to thrive, enter into healthy cells and produce toxins, causing damage to cells.

Studies have been reported that certain yeasts and or molds may be responsible for certain types of cancer.

The foodconsumer.org scientist said that antibiotics are dangerous and should be used as the last line of defense against bacterial infection.   Many infections are caused by viruses and they can not be cured by antibiotics.