Inpharma 1536 - 6 May 2006 Keeping abreast with chemoprevention New agents with better adverse event profiles need to be identified for the chemoprevention of both estrogen- receptor positive and negative breast cancers, writes Dr Ruth M O’Regan from the Winship Cancer Institute, Atlanta, Georgia, US. The role of tamoxifen as a chemopreventive was confirmed when it demonstrated a significant reduction in the incidence of breast cancer in women at high-risk after follow-up of 7 years in the NSABP * P-1 trial. However, tamoxifen was associated with an increase in the incidence of endometrial cancer in women aged > 50 years, and in thromboembolic events. Raloxifene, which is approved for the treatment and prevention of osteoporosis, is also being explored for the chemoprevention of breast cancer. Raloxifene demonstrated a substantial reduction in the incidence of breast cancer in osteoporosis trials. Furthermore, these studies showed that raloxifene did not cause endometrial thickening. However, like tamoxifen, raloxifene was associated with an increased incidence of thromboembolic events. Aromatase inhibitors are superior to tamoxifen for adjuvant treatment of early breast cancer as well as chemoprevention of contralateral breast cancer, with no increase in endometrial cancer and a lower risk of thromboembolic events. Two international studies have been initiated to examine the chemoprevention of breast cancer by aromatase inhibitors. Women with estrogen-receptor negative breast cancers, such as those with BRCA1 mutations, are unlikely to benefit from any current chemopreventives for breast cancer as they all act through the estrogen receptor. Therefore, new agents that act on different pathways, such as trastuzumab or tyrosine kinase inhibitors, need to be investigated for this indication. * National Surgical Adjuvant Breast and Bowel Project O’Regan RM. Chemoprevention of breast cancer. Lancet 367: 1382-1383, No. 9520, 29 Apr 2006 801034136 1 Inpharma 6 May 2006 No. 1536 1173-8324/10/1536-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved

Keeping abreast with chemoprevention

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Inpharma 1536 - 6 May 2006

Keeping abreast withchemoprevention

New agents with better adverse event profiles need tobe identified for the chemoprevention of both estrogen-receptor positive and negative breast cancers, writes DrRuth M O’Regan from the Winship Cancer Institute,Atlanta, Georgia, US.

The role of tamoxifen as a chemopreventive wasconfirmed when it demonstrated a significant reductionin the incidence of breast cancer in women at high-riskafter follow-up of 7 years in the NSABP* P-1 trial.However, tamoxifen was associated with an increase inthe incidence of endometrial cancer in women aged> 50 years, and in thromboembolic events.

Raloxifene, which is approved for the treatment andprevention of osteoporosis, is also being explored forthe chemoprevention of breast cancer. Raloxifenedemonstrated a substantial reduction in the incidence ofbreast cancer in osteoporosis trials. Furthermore, thesestudies showed that raloxifene did not causeendometrial thickening. However, like tamoxifen,raloxifene was associated with an increased incidence ofthromboembolic events.

Aromatase inhibitors are superior to tamoxifen foradjuvant treatment of early breast cancer as well aschemoprevention of contralateral breast cancer, with noincrease in endometrial cancer and a lower risk ofthromboembolic events. Two international studies havebeen initiated to examine the chemoprevention of breastcancer by aromatase inhibitors.

Women with estrogen-receptor negative breastcancers, such as those with BRCA1 mutations, areunlikely to benefit from any current chemopreventivesfor breast cancer as they all act through the estrogenreceptor. Therefore, new agents that act on differentpathways, such as trastuzumab or tyrosine kinaseinhibitors, need to be investigated for this indication.* National Surgical Adjuvant Breast and Bowel Project

O’Regan RM. Chemoprevention of breast cancer. Lancet 367: 1382-1383, No.9520, 29 Apr 2006 801034136