1. V. Ostapenko, T. Pipirienė, K. Valuckas. Primary Chemotherapy in Conservative Treatment of Stage II Breast Cancer Patients. // 6th International Breast Cancer Conference “ABC-98”, Olma Messen, St. Gallen, February 25–28, 1998. The Breast, Vol. 7, p. 78. (Stendinis pranešimas)
2. V. Ostapenko. Combined Treatment of Stage II Breast Cancer Patients. // 10th International Congress on Senology, Porto, Portugal, May 31–June 4, 1998. (Stendinis pranešimas)
3. V. Ostapenko, T. Pipirienė, K. Valuckas. Conservative Treatment of Stage II Breast Cancer Patients. // 17th Cancer Congress, Rio de Janeiro, Brazil, August 23–28, 1998. Abstract Book, p. 127. (Žodinis pranešimas)
4. V. Ostapenko. Breast-Preserving Operation in Conservative Treatment of Early Breast Cancer. // 1st International Congress of Baltic Countries, Tallinn, Estonia, June 25–28, 1998. Abstract Book, pp. 9–10. (Žodinis pranešimas)
5. V. Ostapenko, T. Pipirienė, K. Valuckas. Primary Chemotherapy and Plastic Quadrantectomy in Complex Treatment of Breast Cancer. // II Baltic Congress of Oncology Radiology, Riga, Latvia, September 9–12, 1998, p. 48. (Žodinis pranešimas)
6. V. Ostapenko. Breast-Preserving Operations in Combined Treatment of Stage II Breast Cancer. // Acta Medica Lituanica, 1998, Vol. 5, No. 2, pp. 142–145.
7. V. Ostapenko. Combined Treatment of Stage II Breast Cancer Patients. // 10th International Congress on Senology, Porto, Portugal, May 31–June 4, 1998. Monduzzi Editore, International Proceedings Division, 1998, pp. 697–700.