Breast cancer prevention: present and future

Area of Science:

• Oncology
• Preventive Medicine
• Endocrinology

Background:

• Breast cancer risk is influenced by modifiable factors (hormone levels, obesity, HRT, non-lactation) and non-modifiable factors (genetics, age).
• The impact of easily modifiable factors on overall breast cancer incidence may be limited.
• The Gail model can estimate lifetime breast cancer risk, but prevention strategies like tamoxifen remain debated.

Purpose of the Study:

• To review the impact of various factors on breast cancer risk.
• To evaluate the effectiveness of pharmaceutical interventions (tamoxifen, raloxifene) in breast cancer prevention.
• To assess the influence of lifestyle modifications on breast cancer incidence.

Main Methods:

• Review of clinical trial data (NSABP-P1, Italian, Royal Marsden, MORE trials) evaluating tamoxifen and raloxifene.
• Analysis of epidemiological data on lifestyle factors (diet, obesity, exercise, pregnancy, alcohol intake).
• Examination of studies on other interventions like retinoids, fat reduction, and GnRH analogues.

Main Results:

• Tamoxifen showed a 49% risk reduction in one study (NSABP-P1) but not others, suggesting study-specific effects.
• Raloxifene reduced breast cancer incidence by 65% in the MORE trial, primarily in estrogen receptor-positive tumors.
• Lifestyle factors have a mild to moderate impact; alcohol reduction may offer modest benefits but with potential trade-offs. Retinoids and fat reduction have not shown clear risk reduction benefits.

Conclusions:

• Pharmaceuticals like tamoxifen and raloxifene demonstrate potential for breast cancer risk reduction, particularly raloxifene for ER-positive cancers.
• Lifestyle modifications offer a milder impact on risk reduction compared to pharmaceutical interventions.
• Further research is needed to clarify the role of various factors and interventions in breast cancer prevention.