- Email: [email protected]
P112 The effectiveness of tamoxifen based on the experience of male breast cancer in our institution
14th St.Gallen International Breast Cancer Conference / The Breast 24S1 (2015) S26–S86
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P109 Adjuvant chemotherapy for elderly HER2/neu positive breast cancer patients
P111 The effectiveness of low-dose olanzapine against CINV caused by anthracycline-containing regimen
G. Miryusupova1 *, N. Shayusupov2 . 1 Breast Cancer Surgery, Tashkent City Oncology Center, Tashkent, Uzbekistan, 2 Oncology, Tashkent Pediatric Medical Institute, Tashkent, Uzbekistan
M. Kashiwaba1 *, H. Komatsu1 , K. Ishida1 , R. Kawagishi1 , Y. Matsui1 , H. Otsuki1 , T. Kawasaki2 , N. Uesugi2 , T. Sugai2 , G. Wakabayashi1 . 1 Surgery, Iwate Medical University, Morioka, Japan, 2 Molecular Diagnostic Pathology, Iwate Medical University, Morioka, Japan
Goals: The purpose of our study is to investigate side effects in adjuvant chemotherapy (CT) for elderly breast cancer (BC) patients. Methods: In 21 operable BC patients 63–75 years old, included in trials of adjuvant therapy in our center, 9 women were treated with BC conserving therapy and 12 women received mastectomy. Tumor tissue was defined by negative estrogen receptor and progesterone receptor and positive Her2/neu. All of them were having adjuvant CT with paclitaxel (P) 175 mg/m2 and trastuzumab (T) (8 mg/kg– 6 mg/kg) both every 3 weeks (4 cycles P+T – 6 month T). Results: After 1st cycle of this CT 2 patients had grade 3–4 hematological toxicity (anemia, neutropenia, thrombocytopenia and febrile neutropenia) and 3–4 non-hematological toxicity (abdominal pain, mucositis, neuropathy). We had to reduce P dose by 20% for these patients after 1st cycle of CT. After 2nd cycle of this CT 3 patients had side effects. We had to reduce P dose by 20% too. In this analysis of patients receiving adjuvant CT (P+T) – 5 patients (23.8%) had grade 3–4 hematological and nonhematological side effects. They finished adjuvant CT after reduction of the P dose. Conclusion: Elderly Her2/neu positive BC patients will have need to correct P dose before to starting the adjuvant CT. Disclosure of Interest: No significant relationships. P110 9-week versus 52-week trastuzumab treatment for HER2-positive breast cancer J. Kim *, J. Lee, H. Jeong, W. Byeon. General Surgery, Chungnam National University Hospital, Daejeon, Korea Goals: Trastuzumab has established efficacy against breast cancer with overexpression or amplification of the HER2 oncogene. The current recommendation is 1 year of adjuvant trastuzumab. We compared 9 weeks of treatment with trastuzumab with 52 weeks of treatment in terms of efficacy and toxicity. Methods: This study is a retrospective study comparing treatment with trastuzumab for 9 weeks (every week) and 52 weeks (every 3 weeks) after standard neoadjuvant chemotherapy or adjuvant chemotherapy in 220 patients with HER2-positive breast cancer. Patients who received trastuzumab in the adjuvant treatment were evaluated for disease-free survival (DFS), overall survival (OS), efficacy, and toxicity. Results: There were 90 (40.9%) and 130 (59.1%) patients in the 9- and 52-week trastuzumab groups, respectively. Median follow-up was 73.8 months (14–100) in the 9-week trastuzumab group and 44.5 months (32–61) in the 52-week trastuzumab group. 5-year DFS was 90 and 85% (P = 0.226) in the 9- and 52-week trastuzumab treatment groups, respectively, and 5-year OS was 97.8 and 99.2% in the 9- and 52-week trastuzumab groups, respectively (P = 0.361). There were 9 (10.0%) recurrences and 4 (4.4%) deaths in the 9-week trastuzumab treatment group, and 19 (14.6%) recurrences and 4 (3.1%) deaths in the 52-week trastuzumab treatment group. Toxicity was not observed in the 9-week trastuzumab group and symptomatic cardiotoxicity was observed in 5 (3.8%) patients in the 52-week trastuzumab group. Conclusion: In this study, similar outcomes were found in 9-week group when compared with 52-week trastuzumab treatment group. Disclosure of Interest: No significant relationships.
Goals: Anthracyciline-based regimen (A-regimen) is still important for breast cancer regarding the high risk of CINV. We utilize A-regimen with anti-emesis triplet consisted with aprepitant, dexamethasone and palonosetron, but we observe at least 10% Pts with resistant CINV. Methods: Therefore, we planed to examine the effectiveness of lowdose Olanzapine 2.5 mg/day for four days as a phase II study with resistant CINV after A-regimen treated with anti-emesis triplet in Japanese Pts. Results: Forty patients were entered and it showed significant improvement to resistant CINV (29/40: 72.5%) and no Pts discontinued by adverse events (AE). However, NCCN guideline recommended Olanzapine 10 mg/day for four days, it often shows AE i.e. weight gain, sleepiness and abnormal glucose tolerance. Conclusion: Present study may suggest that even low-dose Olanzapine is an important option for treatment of resistant CINV. Final detailed results will be presented at meeting. Disclosure of Interest: No significant relationships. P112 The effectiveness of tamoxifen based on the experience of male breast cancer in our institution Y. Yoshimura *, M. Fujihara, Y. Kajiwara, M. Kochi, M. Ito, S. Ohtani, K. Higaki. Breast Surgery, Hiroshima City Hiroshima Citizens Hospital, Hiroshima, Japan Goals: For male breast cancer, tamoxifen treatment is suggested to improve disease free survival and overall survival when uesd as adjuvant therapy for 5–10 years. We examined about it in our institution. Methods: 15 male breast cancer patients were operated at our hospital between 1973 and 2014. The median age of them was 69 years (range: 52–79) when they were operated. 2 patients had breast cancer family history. 13 patients had invasive ductal carcinoma, 1 patient had non invasive ductal carcinoma, and 1 patient had mucinous carcinoma. Hormone receptor was determined in 10 patients, all of them were estrogen reseptor positive, 9 of them were progesterone receptor positive, and all of them were human epidermal growth factor receptor negative. All patients had Luminal A like. Total mastectomy performed in 13 patients, partial mastectomy performed in 2 patients. Since 2003, as adjuvant therapy, 8 patients were treated from only tamoxifen (4 of them were treated for over 5 years), 1 patient was treated from FEC (5-FU + epirubicin + cyclophosphamide) and tamoxifen (for over 5 years), and another patient was treated with abraxane, FEC and tamoxifen (for over 5 years). There was no patient treated from aromatase inhibitor. Results: Disease free survival was median 58 months (range: 5–120 months): median 58 months (range: 29–58 months) in not tamoxifen treatment group (5 patients), median 117 months (range: 5–120 months) in tamoxifen treatment group (10 patients) (p = 0.210). Overall survival was median 120 months (range: 5–134 months): median was not reached (range: 29–75 months) in not tamoxifen treatment group, median was not reached (range: 5–134 months) in tamoxifen treatment group. 10 patients are alive, 1 patient died from another disease, and 4 patients are unknown. 4 patients had recurrence or metastasis after median 48 months (range: 31–117 months) from operation. All of them had Luminal A like, 3 of them
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Poster Abstracts I / The Breast 24S1 (2015) S26–S86
had adjuvant therapy including tamoxifen. 3 of 13 patients (23%) who performed from total mastectomy, and 1 of 2 patient (50%) who performed from partial mastectomy had recurrence or metastasis (p = 0.229). After recurrence, they were treated from EC (epirubicin + cyclophosphamide), TC (docetaxel + cyclophosphamide), letrozole, or abraxane, and 3 of them are alive, 1 of them is unknown. Conclusion: It is suggested that tamoxifen treatment as adjuvant therapy may improve disease free survival. Almost all patients are estrogen receptor positive at male breast cancer, therefore tamoxifen can be effective at male breast cancer therapy. Disclosure of Interest: No significant relationships.
Epidemiology/Prevention/Diagnosis P115 Does trastuzumab increase ONJ development due to zoledronic acid treatment in breast cancer? K.N. Pilanci1 *, G. Alco2 , C. Ordu1 , F. Celebi3 , D. Sarsenov4 , Z. Erdogan Iyigun5 , F. Agacayak6 , S. Ilgun4 , V. Ozmen7 . 1 Medical Oncology, Bilim University, Istanbul, Turkey, 2 Radiation Oncology, Gayrettepe Florence Nightingale Hospital, Istanbul, Turkey, 3 Radiology, Gayrettepe Florence Nightingale Hospital, Istanbul, Turkey, 4 Surgery, Istanbul Florence Nightingale Hospital, Istanbul, Turkey, 5 Physical Therapy and Rehabilitation, Bilim University, Istanbul, Turkey, 6 Radiology, Istanbul Florence Nightingale Hospital, Istanbul, Turkey, 7 Surgery, Istanbul Medical Faculty, Istanbul, Turkey Goals: One of the most important adverse effects of Zoledronic acid (ZA) is osteonecrosis of the jaw (ONJ). In the present study, our aim was to evaluate the frequency of this adverse effect, the risk factors influencing its development, and the characteristic features. Patients and Method: Our study included 97 patients with breast cancer recorded in the archives of the Istanbul Florence Nightingale Breast Study Group, who received ZA therapy between March 2006, and December 2013, due to bone metastases. We also recorded the patients’ age, weight, duration of treatment with ZA, number of ZA infusions, dental procedures, concurrent chemotherapy, aromatase inhibitor and/or trastuzumab use, diabetes mellitus, renal dysfunction and smoking habits. Results: The mean age of the patients was 54±10 years and the mean time of exposure to the ZA therapy was 37±18 months. Thirteen patients (13.4%) had developed ONJ. Among the patients with ONJ, the mean time of exposure to ZA was 41 months (range: 13–82 months) and the mean number of ZA infusions was 38 (range: 15–56). The duration of treatment with ZA and the use of trastuzumab were observed to be two factors that influenced the development of ONJ (p = 0.049, p = 0.028, respectively). Table: Multivariate logistic regression analysis (ForwardStepwise) Influential factors in the development of ONJ
OR (95% CI)
p
Trastuzumab use Zoledronic acid use (months)
4.08 (1.159–14.069) 1.032 (1.00–1.065)
0.028 0.049
Conclusion: The development of ONJ may solely be associated with the duration of treatment with ZA but with anti-angiogenic agents received by the patients. We are of the opinion that patients receiving ZA should be followed up with regular dental examinations every 6 to 12 months in order to detect any possible development of ONJ. Disclosure of Interest: No significant relationships.
P116 Alkaline water is ineffective in preventing breast cancer T. Kiskova1 *, V. Demeckova1 , J. Topitzerova1 , S. Gancarcikova2 , D. Mudronova2 , Z. Jendzelovska1 , B. Velika3 , V. Tomeckova3 , M. Backor1 . 1 Faculty of Science, Pavol Jozef Safarik University in Kosice, Kosice, Slovak Republic, 2 University of Veterinary Medicine and Pharmacy, Kosice, Slovak Republic, 3 Faculty of Medicine, Pavol Jozef Safarik University in Kosice, Kosice, Slovak Republic Goals: The information explosion about the impact of an alkaline diet on cancer increased in a few years; up to 4 million web sites are found via the Internet. One of the most popular ways to get more alkaline is to drink alkaline water (pH 8–10). However, there is no credible evidence in scientific literature to support claims that alkaline water (AW) has any greater health effects than drinking regular water. The aim of the study was to evaluate whether daily intake of alkaline water could prevent breast cancer in experimental rats. Methods: Female Sprague-Dawley rats (n = 22) were used in the experiment. Breast cancer was induced with 2 doses of N-methylN-nitrosourea (NMU, 50 mg/kg body weight) on the 43rd and the 50th postnatal day. The prevention with AW began 2 weeks before the 1st NMU dose and its administration ran until the end of the experiment (16 weeks). Rats with NMU-induced mammary tumours were divided into 2 groups: Group 1 (AW, n = 8) was treated with AW (Alkaline Water Pitcher, Yalong Trade, China) ad libitum on a daily basis. Group 2 (NMU, n = 8) was the control untreated group. The intact group (INT, n = 6) consisted of healthy control animals. Basic parameters of carcinogenesis, blood analysis, reactive oxygen species (ROS) in circulating phagocytes, as well as serum biochemistry analyses were determined. Results: The tumour incidence in the AW group reached the incidence of the untreated NMU group (100%) already in the 10th experimental week. The tumour frequency increased significantly (P < 0.05) without influencing the tumour volume. Neither blood nor serum analyses confirmed the protective effect of alkaline water. On the contrary, our data showed a negative effect of AW on selected blood/serum parameters compared to untreated animals. Serum LDL-cholesterol and alkaline phosphatase (ALP) levels were significantly higher (P < 0.05) in the AW group than in the untreated NMU group. The number of blood erythrocytes was significantly lower (P < 0.05) in the AW group compared to the INT group. ROS formation by blood phagocytes in both AW and NMU groups was significantly decreased (P < 0.01) compared to the INT group. Both treated and untreated animals suffered from hypoproteinemia, hypercreatinemia, and hypercalcemia. Conclusion: Our results did not confirm the preventive potential of AW on breast cancer in rats. In contrast, drinking AW alone for an extended period could actually make more damage than help and should therefore be used with caution in patients with breast cancer. An elevated alkaline phosphatase is indicative of bone and liver abnormalities. Recently, it has been shown that high LDL-cholesterol levels promote breast cancer progression. It is therefore not surprising that the only group, where we observed death during the experimental period, was the AW group. Our work is the first scientific evidence that alkaline water is not only ineffective primary prevention of breast cancer but can promote the process of carcinogenesis. Disclosure of Interest: No significant relationships.
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P109 Adjuvant chemotherapy for elderly HER2/neu positive breast cancer patients
P111 The effectiveness of low-dose olanzapine against CINV caused by anthracycline-containing regimen
G. Miryusupova1 *, N. Shayusupov2 . 1 Breast Cancer Surgery, Tashkent City Oncology Center, Tashkent, Uzbekistan, 2 Oncology, Tashkent Pediatric Medical Institute, Tashkent, Uzbekistan
M. Kashiwaba1 *, H. Komatsu1 , K. Ishida1 , R. Kawagishi1 , Y. Matsui1 , H. Otsuki1 , T. Kawasaki2 , N. Uesugi2 , T. Sugai2 , G. Wakabayashi1 . 1 Surgery, Iwate Medical University, Morioka, Japan, 2 Molecular Diagnostic Pathology, Iwate Medical University, Morioka, Japan
Goals: The purpose of our study is to investigate side effects in adjuvant chemotherapy (CT) for elderly breast cancer (BC) patients. Methods: In 21 operable BC patients 63–75 years old, included in trials of adjuvant therapy in our center, 9 women were treated with BC conserving therapy and 12 women received mastectomy. Tumor tissue was defined by negative estrogen receptor and progesterone receptor and positive Her2/neu. All of them were having adjuvant CT with paclitaxel (P) 175 mg/m2 and trastuzumab (T) (8 mg/kg– 6 mg/kg) both every 3 weeks (4 cycles P+T – 6 month T). Results: After 1st cycle of this CT 2 patients had grade 3–4 hematological toxicity (anemia, neutropenia, thrombocytopenia and febrile neutropenia) and 3–4 non-hematological toxicity (abdominal pain, mucositis, neuropathy). We had to reduce P dose by 20% for these patients after 1st cycle of CT. After 2nd cycle of this CT 3 patients had side effects. We had to reduce P dose by 20% too. In this analysis of patients receiving adjuvant CT (P+T) – 5 patients (23.8%) had grade 3–4 hematological and nonhematological side effects. They finished adjuvant CT after reduction of the P dose. Conclusion: Elderly Her2/neu positive BC patients will have need to correct P dose before to starting the adjuvant CT. Disclosure of Interest: No significant relationships. P110 9-week versus 52-week trastuzumab treatment for HER2-positive breast cancer J. Kim *, J. Lee, H. Jeong, W. Byeon. General Surgery, Chungnam National University Hospital, Daejeon, Korea Goals: Trastuzumab has established efficacy against breast cancer with overexpression or amplification of the HER2 oncogene. The current recommendation is 1 year of adjuvant trastuzumab. We compared 9 weeks of treatment with trastuzumab with 52 weeks of treatment in terms of efficacy and toxicity. Methods: This study is a retrospective study comparing treatment with trastuzumab for 9 weeks (every week) and 52 weeks (every 3 weeks) after standard neoadjuvant chemotherapy or adjuvant chemotherapy in 220 patients with HER2-positive breast cancer. Patients who received trastuzumab in the adjuvant treatment were evaluated for disease-free survival (DFS), overall survival (OS), efficacy, and toxicity. Results: There were 90 (40.9%) and 130 (59.1%) patients in the 9- and 52-week trastuzumab groups, respectively. Median follow-up was 73.8 months (14–100) in the 9-week trastuzumab group and 44.5 months (32–61) in the 52-week trastuzumab group. 5-year DFS was 90 and 85% (P = 0.226) in the 9- and 52-week trastuzumab treatment groups, respectively, and 5-year OS was 97.8 and 99.2% in the 9- and 52-week trastuzumab groups, respectively (P = 0.361). There were 9 (10.0%) recurrences and 4 (4.4%) deaths in the 9-week trastuzumab treatment group, and 19 (14.6%) recurrences and 4 (3.1%) deaths in the 52-week trastuzumab treatment group. Toxicity was not observed in the 9-week trastuzumab group and symptomatic cardiotoxicity was observed in 5 (3.8%) patients in the 52-week trastuzumab group. Conclusion: In this study, similar outcomes were found in 9-week group when compared with 52-week trastuzumab treatment group. Disclosure of Interest: No significant relationships.
Goals: Anthracyciline-based regimen (A-regimen) is still important for breast cancer regarding the high risk of CINV. We utilize A-regimen with anti-emesis triplet consisted with aprepitant, dexamethasone and palonosetron, but we observe at least 10% Pts with resistant CINV. Methods: Therefore, we planed to examine the effectiveness of lowdose Olanzapine 2.5 mg/day for four days as a phase II study with resistant CINV after A-regimen treated with anti-emesis triplet in Japanese Pts. Results: Forty patients were entered and it showed significant improvement to resistant CINV (29/40: 72.5%) and no Pts discontinued by adverse events (AE). However, NCCN guideline recommended Olanzapine 10 mg/day for four days, it often shows AE i.e. weight gain, sleepiness and abnormal glucose tolerance. Conclusion: Present study may suggest that even low-dose Olanzapine is an important option for treatment of resistant CINV. Final detailed results will be presented at meeting. Disclosure of Interest: No significant relationships. P112 The effectiveness of tamoxifen based on the experience of male breast cancer in our institution Y. Yoshimura *, M. Fujihara, Y. Kajiwara, M. Kochi, M. Ito, S. Ohtani, K. Higaki. Breast Surgery, Hiroshima City Hiroshima Citizens Hospital, Hiroshima, Japan Goals: For male breast cancer, tamoxifen treatment is suggested to improve disease free survival and overall survival when uesd as adjuvant therapy for 5–10 years. We examined about it in our institution. Methods: 15 male breast cancer patients were operated at our hospital between 1973 and 2014. The median age of them was 69 years (range: 52–79) when they were operated. 2 patients had breast cancer family history. 13 patients had invasive ductal carcinoma, 1 patient had non invasive ductal carcinoma, and 1 patient had mucinous carcinoma. Hormone receptor was determined in 10 patients, all of them were estrogen reseptor positive, 9 of them were progesterone receptor positive, and all of them were human epidermal growth factor receptor negative. All patients had Luminal A like. Total mastectomy performed in 13 patients, partial mastectomy performed in 2 patients. Since 2003, as adjuvant therapy, 8 patients were treated from only tamoxifen (4 of them were treated for over 5 years), 1 patient was treated from FEC (5-FU + epirubicin + cyclophosphamide) and tamoxifen (for over 5 years), and another patient was treated with abraxane, FEC and tamoxifen (for over 5 years). There was no patient treated from aromatase inhibitor. Results: Disease free survival was median 58 months (range: 5–120 months): median 58 months (range: 29–58 months) in not tamoxifen treatment group (5 patients), median 117 months (range: 5–120 months) in tamoxifen treatment group (10 patients) (p = 0.210). Overall survival was median 120 months (range: 5–134 months): median was not reached (range: 29–75 months) in not tamoxifen treatment group, median was not reached (range: 5–134 months) in tamoxifen treatment group. 10 patients are alive, 1 patient died from another disease, and 4 patients are unknown. 4 patients had recurrence or metastasis after median 48 months (range: 31–117 months) from operation. All of them had Luminal A like, 3 of them
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Poster Abstracts I / The Breast 24S1 (2015) S26–S86
had adjuvant therapy including tamoxifen. 3 of 13 patients (23%) who performed from total mastectomy, and 1 of 2 patient (50%) who performed from partial mastectomy had recurrence or metastasis (p = 0.229). After recurrence, they were treated from EC (epirubicin + cyclophosphamide), TC (docetaxel + cyclophosphamide), letrozole, or abraxane, and 3 of them are alive, 1 of them is unknown. Conclusion: It is suggested that tamoxifen treatment as adjuvant therapy may improve disease free survival. Almost all patients are estrogen receptor positive at male breast cancer, therefore tamoxifen can be effective at male breast cancer therapy. Disclosure of Interest: No significant relationships.
Epidemiology/Prevention/Diagnosis P115 Does trastuzumab increase ONJ development due to zoledronic acid treatment in breast cancer? K.N. Pilanci1 *, G. Alco2 , C. Ordu1 , F. Celebi3 , D. Sarsenov4 , Z. Erdogan Iyigun5 , F. Agacayak6 , S. Ilgun4 , V. Ozmen7 . 1 Medical Oncology, Bilim University, Istanbul, Turkey, 2 Radiation Oncology, Gayrettepe Florence Nightingale Hospital, Istanbul, Turkey, 3 Radiology, Gayrettepe Florence Nightingale Hospital, Istanbul, Turkey, 4 Surgery, Istanbul Florence Nightingale Hospital, Istanbul, Turkey, 5 Physical Therapy and Rehabilitation, Bilim University, Istanbul, Turkey, 6 Radiology, Istanbul Florence Nightingale Hospital, Istanbul, Turkey, 7 Surgery, Istanbul Medical Faculty, Istanbul, Turkey Goals: One of the most important adverse effects of Zoledronic acid (ZA) is osteonecrosis of the jaw (ONJ). In the present study, our aim was to evaluate the frequency of this adverse effect, the risk factors influencing its development, and the characteristic features. Patients and Method: Our study included 97 patients with breast cancer recorded in the archives of the Istanbul Florence Nightingale Breast Study Group, who received ZA therapy between March 2006, and December 2013, due to bone metastases. We also recorded the patients’ age, weight, duration of treatment with ZA, number of ZA infusions, dental procedures, concurrent chemotherapy, aromatase inhibitor and/or trastuzumab use, diabetes mellitus, renal dysfunction and smoking habits. Results: The mean age of the patients was 54±10 years and the mean time of exposure to the ZA therapy was 37±18 months. Thirteen patients (13.4%) had developed ONJ. Among the patients with ONJ, the mean time of exposure to ZA was 41 months (range: 13–82 months) and the mean number of ZA infusions was 38 (range: 15–56). The duration of treatment with ZA and the use of trastuzumab were observed to be two factors that influenced the development of ONJ (p = 0.049, p = 0.028, respectively). Table: Multivariate logistic regression analysis (ForwardStepwise) Influential factors in the development of ONJ
OR (95% CI)
p
Trastuzumab use Zoledronic acid use (months)
4.08 (1.159–14.069) 1.032 (1.00–1.065)
0.028 0.049
Conclusion: The development of ONJ may solely be associated with the duration of treatment with ZA but with anti-angiogenic agents received by the patients. We are of the opinion that patients receiving ZA should be followed up with regular dental examinations every 6 to 12 months in order to detect any possible development of ONJ. Disclosure of Interest: No significant relationships.
P116 Alkaline water is ineffective in preventing breast cancer T. Kiskova1 *, V. Demeckova1 , J. Topitzerova1 , S. Gancarcikova2 , D. Mudronova2 , Z. Jendzelovska1 , B. Velika3 , V. Tomeckova3 , M. Backor1 . 1 Faculty of Science, Pavol Jozef Safarik University in Kosice, Kosice, Slovak Republic, 2 University of Veterinary Medicine and Pharmacy, Kosice, Slovak Republic, 3 Faculty of Medicine, Pavol Jozef Safarik University in Kosice, Kosice, Slovak Republic Goals: The information explosion about the impact of an alkaline diet on cancer increased in a few years; up to 4 million web sites are found via the Internet. One of the most popular ways to get more alkaline is to drink alkaline water (pH 8–10). However, there is no credible evidence in scientific literature to support claims that alkaline water (AW) has any greater health effects than drinking regular water. The aim of the study was to evaluate whether daily intake of alkaline water could prevent breast cancer in experimental rats. Methods: Female Sprague-Dawley rats (n = 22) were used in the experiment. Breast cancer was induced with 2 doses of N-methylN-nitrosourea (NMU, 50 mg/kg body weight) on the 43rd and the 50th postnatal day. The prevention with AW began 2 weeks before the 1st NMU dose and its administration ran until the end of the experiment (16 weeks). Rats with NMU-induced mammary tumours were divided into 2 groups: Group 1 (AW, n = 8) was treated with AW (Alkaline Water Pitcher, Yalong Trade, China) ad libitum on a daily basis. Group 2 (NMU, n = 8) was the control untreated group. The intact group (INT, n = 6) consisted of healthy control animals. Basic parameters of carcinogenesis, blood analysis, reactive oxygen species (ROS) in circulating phagocytes, as well as serum biochemistry analyses were determined. Results: The tumour incidence in the AW group reached the incidence of the untreated NMU group (100%) already in the 10th experimental week. The tumour frequency increased significantly (P < 0.05) without influencing the tumour volume. Neither blood nor serum analyses confirmed the protective effect of alkaline water. On the contrary, our data showed a negative effect of AW on selected blood/serum parameters compared to untreated animals. Serum LDL-cholesterol and alkaline phosphatase (ALP) levels were significantly higher (P < 0.05) in the AW group than in the untreated NMU group. The number of blood erythrocytes was significantly lower (P < 0.05) in the AW group compared to the INT group. ROS formation by blood phagocytes in both AW and NMU groups was significantly decreased (P < 0.01) compared to the INT group. Both treated and untreated animals suffered from hypoproteinemia, hypercreatinemia, and hypercalcemia. Conclusion: Our results did not confirm the preventive potential of AW on breast cancer in rats. In contrast, drinking AW alone for an extended period could actually make more damage than help and should therefore be used with caution in patients with breast cancer. An elevated alkaline phosphatase is indicative of bone and liver abnormalities. Recently, it has been shown that high LDL-cholesterol levels promote breast cancer progression. It is therefore not surprising that the only group, where we observed death during the experimental period, was the AW group. Our work is the first scientific evidence that alkaline water is not only ineffective primary prevention of breast cancer but can promote the process of carcinogenesis. Disclosure of Interest: No significant relationships.