Metastatic Breast Cancer: Tamoxifen citrate tablets, USP are effective in the treatment of metastatic breast cancer in women and men. In premenopausal women with metastatic breast cancer, tamoxifen is an alternative to oophorectomy or ovarian irradiation. Available evidence indicates that patients whose tumors are estrogen receptor positive are more likely to benefit from tamoxifen therapy. Adjuvant Treatment of Breast Cancer: Tamoxifen citrate tablets, USP are indicated for the treatment of node-positive breast cancer in women following total mastectomy or segmental mastectomy, axillary dissection, and breast irradiation.
In some tamoxifen adjuvant studies, most of the benefit to date has been in the subgroup with four or more positive axillary nodes. Tamoxifen citrate tablets, USP are indicated for the treatment of axillary node-negative breast cancer in women following total mastectomy or segmental mastectomy, axillary dissection, and breast irradiation. The estrogen and progesterone receptor values may help to predict whether adjuvant tamoxifen therapy is likely to be beneficial.
Tamoxifen reduces the occurrence of contralateral breast cancer in patients receiving adjuvant tamoxifen therapy for breast cancer. Ductal Carcinoma in Situ (DCIS): In women with DCIS, following breast surgery and radiation, tamoxifen citrate tablets are indicated to reduce the risk of invasive breast cancer (see BOXED WARNING at the beginning of the label). The decision regarding therapy with tamoxifen for the reduction in breast cancer incidence should be based upon an individual assessment of the benefits and risks of tamoxifen therapy.
Current data from clinical trials support 5 years of adjuvant tamoxifen therapy for patients with breast cancer. Reduction in Breast Cancer Incidence in High Risk Women: Tamoxifen citrate tablets are indicated to reduce the incidence of breast cancer in women at high risk for breast cancer. This effect was shown in a study of 5 years planned duration with a median follow-up of 4.2 years. Twenty-five percent of the participants received drug for 5 years.
The longer-term effects are not known. In this study, there was no impact of tamoxifen on overall or breast cancer-related mortality (see BOXED WARNING at the beginning of the label). Tamoxifen citrate tablets are indicated only for high-risk women. “High risk” is defined as women at least 35 years of age with a 5-year predicted risk of breast cancer greater than or equal to 1.67%, as calculated by the Gail Model. Examples of combinations of factors predicting a 5-year risk greater than or equal to 1.67% are: Age 35 or older and any of the following combination of factors:
One first degree relative with a history of breast cancer, 2 or more benign biopsies, and a history of a breast biopsy showing atypical hyperplasia; or
At least 2 first degree relatives with a history of breast cancer, and a personal history of at least one breast biopsy; or
LCIS Age 40 or older and any of the following combination of factors:
One first degree relative with a history of breast cancer, 2 or more benign biopsies, age at first live birth 25 or older, and age at menarche 11 or younger; or
At least 2 first degree relatives with a history of breast cancer, and age at first live birth 19 or younger; or
One first degree relative with a history of breast cancer, and a personal history of a breast biopsy showing atypical hyperplasia. Age 45 or older and any of the following combination of factors:
At least 2 first degree relatives with a history of breast cancer and age at first live birth 24 or younger; or
One first degree relative with a history of breast cancer with a personal history of a benign breast biopsy, age at menarche 11 or less and age at first live birth 20 or more. Age 50 or older and any of the following combination of factors:
At least 2 first degree relatives with a history of breast cancer; or
History of 1 breast biopsy showing atypical hyperplasia, and age at first live birth 30 or older and age at menarche 11 or less; or
History of at least 2 breast biopsies with a history of atypical hyperplasia, and age at first live birth 30 or more. Age 55 or older and any of the following combination of factors:
One first degree relative with a history of breast cancer with a personal history of a benign breast biopsy, and age at menarche 11 or less; or
History of at least 2 breast biopsies with a history of atypical hyperplasia, and age at first live birth 20 or older. Age 60 or older and:
Five-year predicted risk of breast cancer greater than or equal to 1.67%, as calculated by the Gail Model. For women whose risk factors are not described in the above examples, the Gail Model is necessary to estimate absolute breast cancer risk. Health Care Professionals can obtain a Gail Model Risk Assessment Tool by dialing 1-800-272-5525. There are insufficient data available regarding the effect of tamoxifen on breast cancer incidence in women with inherited mutations (BRCA1, BRCA2) to be able to make specific recommendations on the effectiveness of tamoxifen citrate in these patients. After an assessment of the risk of developing breast cancer, the decision regarding therapy with tamoxifen for the reduction in breast cancer incidence should be based upon an individual assessment of the benefits and risks of tamoxifen citrate therapy. In the NSABP P-1 trial, tamoxifen treatment lowered the risk of developing breast cancer during the follow-up period of the trial, but did not eliminate breast cancer risk (see Table 3 in CLINICAL PHARMACOLOGY ).
Contraindications
Tamoxifen citrate tablets are contraindicated in patients with known hypersensitivity to the drug or any of its ingredients. Reduction in Breast Cancer Incidence in High Risk Women and Women with DCIS: Tamoxifen citrate tablets are contraindicated in women who require concomitant coumarin-type anticoagulant therapy or in women with a history of deep-vein thrombosis or pulmonary embolus.
Warnings and precautions
Effects in Metastatic Breast Cancer Patients: As with other additive hormonal therapy (estrogens and androgens), hypercalcemia has been reported in some breast cancer patients with bone metastases within a few weeks of starting treatment with tamoxifen. If hypercalcemia does occur, appropriate measures should be taken and, if severe, tamoxifen should be discontinued. Effects on the Uterus-Endometrial Cancer and Uterine Sarcoma: An increased incidence of uterine malignancies has been reported in association with tamoxifen treatment.
The underlying mechanism is unknown, but may be related to the estrogen-like effect of tamoxifen. Most uterine malignancies seen in association with tamoxifen are classified as adenocarcinoma of the endometrium. However, rare uterine sarcomas, including malignant mixed mullerian tumors (MMMT), have also been reported. Uterine sarcoma is generally associated with a higher FIGO stage (III/IV) at diagnosis, poorer prognosis, and shorter survival.
Uterine sarcoma has been reported to occur more frequently among long-term users (greater than or equal to 2 years) of tamoxifen citrate than non-users. Some of the uterine malignancies (endometrial carcinoma or uterine sarcoma) have been fatal. In the NSABP P-1 trial, among participants randomized to tamoxifen there was a statistically significant increase in the incidence of endometrial cancer (33 cases of invasive endometrial cancer, compared to 14 cases among participants randomized to placebo (RR=2.48, 95% CI: 1.27 to 4.92).
The 33 cases in participants receiving tamoxifen were FIGO Stage I, including 20 IA, 12 IB, and 1 IC endometrial adenocarcinomas. In participants randomized to placebo, 13 were FIGO Stage I (8 IA and 5 IB) and 1 was FIGO Stage IV. Five women on tamoxifen citrate and 1 on placebo received postoperative radiation therapy in addition to surgery. This increase was primarily observed among women at least 50 years of age at the time of randomization (26 cases of invasive endometrial cancer, compared to 6 cases among participants randomized to placebo (RR=4.50, 95% CI: 1.78 to 13.16).
Among women less than or equal to 49 years of age at the time of randomization there were 7 cases of invasive endometrial cancer, compared to 8 cases among participants randomized to placebo (RR=0.94, 95% CI: 0.28 to 2.89). If age at the time of diagnosis is considered, there were 4 cases of endometrial cancer among participants less than or equal to 49 randomized to tamoxifen compared to 2 among participants randomized to placebo (RR=2.21, 95% CI: 0.4 to 12.0).
For women greater than or equal to 50 at the time of diagnosis, there were 29 cases among participants randomized to tamoxifen compared to 12 among women on placebo (RR=2.5, 95% CI: 1.3 to 4.9). The risk ratios were similar in the two groups, although fewer events occurred in younger women. Most (29 of 33 cases in the tamoxifen group) endometrial cancers were diagnosed in symptomatic women, although 5 of 33 cases in the tamoxifen group occurred in asymptomatic women.
Among women receiving tamoxifen the events appeared between 1 and 61 months (average=32 months) from the start of treatment. In an updated review of long-term data (median length of total follow-up is 6.9 years, including blinded follow-up) on 8,306 women with an intact uterus at randomization in the NSABP P-1 risk reduction trial, the incidence of both adenocarcinomas and rare uterine sarcomas was increased in women taking tamoxifen.
During blinded follow-up, there were 36 cases of FIGO Stage I endometrial adenocarcinoma (22 were FIGO Stage IA, 13 IB, and 1 IC) in women receiving tamoxifen and 15 cases in women receiving placebo [14 were FIGO Stage I (9 IA and 5 IB), and 1 case was FIGO Stage IV]. Of the patients receiving tamoxifen who developed endometrial cancer, one with Stage IA and 4 with Stage IB cancers received radiation therapy. In the placebo group, one patient with FIGO Stage IB cancer received radiation therapy and the patient with FIGO Stage IVB cancer received chemotherapy and hormonal therapy.
During total follow-up, endometrial adenocarcinoma was reported in 53 women randomized to tamoxifen (30 cases of FIGO Stage IA, 20 were Stage IB, 1 was Stage IC, and 2 were Stage IIIC), and 17 women randomized to placebo (9 cases were FIGO Stage IA, 6 were Stage IB, 1 was Stage IIIC, and 1 was Stage IVB) (incidence per 1000 women-years of 2.20 and 0.71, respectively). Some patients received post-operative radiation therapy in addition to surgery.
Uterine sarcomas were reported in 4 women randomized to tamoxifen (1 was FIGO IA, 1 was FIGO IB, 1 was FIGO IIA, and 1 was FIGO IIIC) and 1 patient randomized to placebo (FIGO 1A); incidence per 1000 women-years of 0.17 and 0.04, respectively. Of the patients randomized to tamoxifen, the FIGO IA and IB cases were a MMMT and sarcoma, respectively; the FIGO II was a MMMT; and the FIGO III was a sarcoma; and the 1 patient randomized to placebo had a MMMT.
A similar increased incidence in endometrial adenocarcinoma and uterine sarcoma was observed among women receiving tamoxifen in 5 other NSABP clinical trials. Any patient receiving or who has previously received tamoxifen who reports abnormal vaginal bleeding should be promptly evaluated. Patients receiving or who have previously received tamoxifen should have annual gynecological examinations and they should promptly inform their physicians if they experience any abnormal gynecological symptoms, e.g., menstrual irregularities, abnormal vaginal bleeding, changes in vaginal discharge, or pelvic pain or pressure.
In the P-1 trial, endometrial sampling did not alter the endometrial cancer detection rate compared to women who did not undergo endometrial sampling (0.6% with sampling, 0.5% without sampling) for women with an intact uterus. There are no data to suggest that routine endometrial sampling in asymptomatic women taking tamoxifen to reduce the incidence of breast cancer would be beneficial. Non-Malignant Effects on the Uterus: An increased incidence of endometrial changes including hyperplasia and polyps has been reported in association with tamoxifen treatment.
The incidence and pattern of this increase suggest that the underlying mechanism is related to the estrogenic properties of tamoxifen. There have been a few reports of endometriosis and uterine fibroids in women receiving tamoxifen. The underlying mechanism may be due to the partial estrogenic effect of tamoxifen. Ovarian cysts have also been observed in a small number of premenopausal patients with advanced breast cancer who have been treated with tamoxifen.
Tamoxifen has been reported to cause menstrual irregularity or amenorrhea. Thromboembolic Effects of Tamoxifen: There is evidence of an increased incidence of thromboembolic events, including deep-vein thrombosis and pulmonary embolism, during tamoxifen therapy. When tamoxifen is coadministered with chemotherapy, there may be a further increase in the incidence of thromboembolic effects. For treatment of breast cancer, the risks and benefits of tamoxifen should be carefully considered in women with a history of thromboembolic events.
In a small substudy (N=81) of the NSABP P-1 trial, there appeared to be no benefit to screening women for Factor V Leiden and Prothrombin mutations G20210A as a means to identify those who may not be appropriate candidates for tamoxifen therapy. Data from the NSABP P-1 trial show that participants receiving tamoxifen without a history of pulmonary emboli (PE) had a statistically significant increase in pulmonary emboli (18-tamoxifen, 6-placebo; RR=3.01, 95% CI: 1.15 to 9.27).
Three of the pulmonary emboli, all in the tamoxifen arm, were fatal. Eighty-seven percent of the cases of pulmonary embolism occurred in women at least 50 years of age at randomization. Among women receiving tamoxifen, the events appeared between 2 and 60 months (average = 27 months) from the start of treatment. In this same population, a
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Interactions
Drug Interactions: When tamoxifen is used in combination with coumarin-type anticoagulants, a significant increase in anticoagulant effect may occur. Where such coadministration exists, careful monitoring of the patient's prothrombin time is recommended. In the NSABP P-1 trial, women who required coumarin-type anticoagulants for any reason were ineligible for participation in the trial (see CONTRAINDICATIONS ). There is an increased risk of thromboembolic events occurring when cytotoxic agents are used in combination with tamoxifen.
Tamoxifen reduced letrozole plasma concentrations by 37%. The effect of tamoxifen on metabolism and excretion of other antineoplastic drugs, such as cyclophosphamide and other drugs that require mixed function oxidases for activation, is not known. Tamoxifen and N-desmethyl tamoxifen plasma concentrations have been shown to be reduced when coadministered with rifampin or aminoglutethimide. Induction of CYP3A4-mediated metabolism is considered to be the mechanism by which these reductions occur; other CYP3A4 inducing agents have not been studied to confirm this effect.
One patient receiving tamoxifen with concomitant phenobarbital exhibited a steady-state serum level of tamoxifen lower than that observed for other patients (i.e., 26 ng/mL vs. mean value of 122 ng/mL). However, the clinical significance of this finding is not known. Rifampin induced the metabolism of tamoxifen and significantly reduced the plasma concentrations of tamoxifen in 10 patients. Aminoglutethimide reduces tamoxifen and N-desmethyl tamoxifen plasma concentrations.
Medroxyprogesterone reduces plasma concentrations of N-desmethyl, but not tamoxifen. Concomitant bromocriptine therapy has been shown to elevate serum tamoxifen and N-desmethyl tamoxifen. Based on clinical and pharmacokinetic results from the anastrozole adjuvant trial, tamoxifen citrate should not be administered with anastrozole (see CLINICAL PHARMACOLOGY, Drug-Drug Interactions ).
Pregnancy and breastfeeding
Pregnancy Teratogenic Effects Pregnancy Category D See WARNINGS .
Adverse reactions
Adverse reactions to tamoxifen are relatively mild and rarely severe enough to require discontinuation of treatment in breast cancer patients. Continued clinical studies have resulted in further information which better indicates the incidence of adverse reactions with tamoxifen as compared to placebo. Metastatic Breast Cancer: Increased bone and tumor pain and, also, local disease flare have occurred, which are sometimes associated with a good tumor response.
Patients with increased bone pain may require additional analgesics. Patients with soft tissue disease may have sudden increases in the size of preexisting lesions, sometimes associated with marked erythema within and surrounding the lesions and/or the development of new lesions. When they occur, the bone pain or disease flare are seen shortly after starting tamoxifen and generally subside rapidly. In patients treated with tamoxifen for metastatic breast cancer, the most frequent adverse reaction to tamoxifen is hot flashes.
Other adverse reactions which are seen infrequently are hypercalcemia, peripheral edema, distaste for food, pruritus vulvae, depression, dizziness, light-headedness, headache, hair thinning and/or partial hair loss, and vaginal dryness. Premenopausal Women: The following table summarizes the incidence of adverse reactions reported at a frequency of 2% or greater from clinical trials (Ingle, Pritchard, Buchanan) which compared tamoxifen therapy to ovarian ablation in premenopausal patients with metastatic breast cancer.
TAMOXIFEN All Effects % of Women OVARIAN ABLATION All Effects % of Women Adverse Reactions* n=104 n=100 Flush 33 46 Amenorrhea 16 69 Altered Menses 13 5 Oligomenorrhea 9 1 Bone Pain 6 6 Menstrual Disorder 6 4 Nausea 5 4 Cough/Coughing 4 1 Edema 4 1 Fatigue 4 1 Musculoskeletal Pain 3 0 Pain 3 4 Ovarian Cyst(s) 3 2 Depression 2 2 Abdominal Cramps 1 2 Anorexia 1 2 *Some women had more than one adverse reaction. Male Breast Cancer: Tamoxifen is well tolerated in males with breast cancer.
Reports from the literature and case reports suggest that the safety profile of tamoxifen in males is similar to that seen in women. Loss of libido and impotence have resulted in discontinuation of tamoxifen therapy in male patients. Also, in oligospermic males treated with tamoxifen, LH, FSH, testosterone and estrogen levels were elevated. No significant clinical changes were reported. Adjuvant Breast Cancer: In the NSABP B-14 study, women with axillary node-negative breast cancer were randomized to 5 years of tamoxifen 20 mg/day or placebo following primary surgery.
The reported adverse effects are tabulated below (mean follow-up of approximately 6.8 years) showing adverse events more common on tamoxifen than on placebo. The incidence of hot flashes (64% vs. 48%), vaginal discharge (30% vs. 15%), and irregular menses (25% vs. 19%) were higher with tamoxifen compared with placebo. All other adverse effects occurred with similar frequency in the 2 treatment groups, with the exception of thrombotic events; a higher incidence was seen in tamoxifen-treated patients (through 5 years, 1.7% vs. 0.4%).
Two of the patients treated with tamoxifen who had thrombotic events died. NSABP B-14 Study % of Women Adverse Effect TAMOXIFEN (n=1422) PLACEBO (n=1437) Hot Flashes 64 48 Fluid Retention 32 30 Vaginal Discharge 30 15 Nausea 26 24 Irregular Menses 25 19 Weight Loss (>5%) 23 18 Skin Changes 19 15 Increased SGOT 5 3 Increased Bilirubin 2 1 Increased Creatinine 2 1 Thrombocytopenia * 2 1 Thrombotic Events Deep Vein Thrombosis 0.8
0.2 Pulmonary Embolism 0.5
0.2Superficial Phlebitis 0.4
0.0 *Defined as a platelet count of less than 100,000/mm 3 In the Eastern Cooperative Oncology Group (ECOG) adjuvant breast cancer trial, tamoxifen or placebo was administered for 2 years to women following mastectomy. When compared to placebo, tamoxifen showed a significantly higher incidence of hot flashes (19% vs. 8% for placebo). The incidence of all other adverse reactions was similar in the 2 treatment groups with the exception of thrombocytopenia where the incidence for tamoxifen was 10% vs. 3% for placebo, an observation of borderline statistical significance.
In other adjuvant studies, Toronto and Tamoxifen Adjuvant Trial Organization (NATO), women received either tamoxifen or no therapy. In the Toronto study, hot flashes were observed in 29% of patients for tamoxifen vs. 1% in the untreated group. In the NATO trial, hot flashes and vaginal bleeding were reported in 2.8%, and 2.0% of women, respectively, for tamoxifen vs. 0.2% for each in the untreated group. Anastrozole Adjuvant Trial - Study of Anastrozole Compared to Tamoxifen for Adjuvant Treatment of Early Breast Cancer (see CLINICAL PHARMACOLOGY, Clinical Studies ).
At a median follow-up of 33 months, the combination of anastrozole and tamoxifen citrate did not demonstrate any efficacy benefit when compared to tamoxifen therapy given alone in all patients as well as in the hormone receptor positive subpopulation. This treatment arm was discontinued from the trial. The median duration of adjuvant treatment for safety evaluation was 59.8 months and 59.6 months for patients receiving anastrozole 1 mg and tamoxifen 20 mg, respectively.
Adverse events occurring with an incidence of at least 5% in either treatment group during treatment or within 14 days of the end of treatment are presented in the following table. Adverse events occurring with an incidence of at least 5% in either treatment group during treatment, or within 14 days of the end of treatment Body system and adverse event by COSTART-preferred term* Anastrozole 1 mg (N = 3092) TAMOXIFEN 20 mg (N = 3094) Body as a whole Asthenia 575 (19) 544 (18) Pain 533 (17) 485 (16) Back pain 321 (10) 309 (10) Headache 314 (10) 249 (8) Abdominal pain 271 (9) 276 (9) Infection 285 (9) 276 (9) Accidental injury 311 (10) 303 (10) Flu syndrome 175 (6) 195 (6) Chest pain 200 (7) 150 (5) Neoplasm 162 (5) 144 (5) Cyst 138 (5) 162 (5) Cardiovascular Vasodilatation 1104 (36) 1264 (41) Hypertension 402 (13) 349 (11) Digestive Nausea 343 (11) 335 (11) Constipation 249 (8) 252 (8) Diarrhea 265 (9) 216 (7) Dyspepsia 206 (7) 169 (6) Gastrointestinal disorder 210 (7) 158 (5) Hemic and lymphatic Lymphoedema 304 (10) 341 (11) Anemia 113 (4) 159 (5) Metabolic and nutritional Peripheral edema 311 (10) 343 (11) Weight gain 285 (9) 274 (9) Hypercholesterolemia 278 (9) 108 (3.5) Musculoskeletal Arthritis 512 (17) 445 (14) Arthralgia 467 (15) 344 (11) Osteoporosis 325 (11) 226 (7) Fracture 315 (10) 209 (7) Bone pain 201 (7) 185 (6) Arthrosis 207 (7) 156 (5) Joint Disorder 184 (6) 160 (5) Myalgia 179 (6) 160 (5) Nervous system Depression 413 (13) 382 (12) Insomnia 309 (10) 281 (9) Dizziness 236 (8) 234 (8) Anxiety 195 (6) 180 (6) Paraesthesia 215 (7) 145 (5) Respiratory Pharyngitis 443 (14) 422 (14) Cough increased 261 (8) 287 (9) Dyspnea 234 (8) 237 (8) Sinusitis 184 (6) 159 (5) Bronchitis 167 (5) 153 (5) Skin and appendages Rash 333 (11) 387 (13) Sweating 145 (5) 177 (6) Special Senses Cataract specified 182 (6) 213 (7) Urogenital Leukorrhea 86 (3) 286 (9) Urinary tract infection 244 (8) 313 (10) Breast pain 251 (8) 169 (6) Breast neoplasm 164 (5) 139 (5) Vulvovaginitis 194 (6) 150 (5) Vaginal hemorrhage† 122 (4) 180 (6) Vaginitis 125 (4) 158 (5) COSTART Coding Symbols for Thesaurus of Adverse Reaction Terms.
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Composition
Active ingredients
TAMOXIFEN CITRATE EQ 10MG BASE
Strengths and forms
The FDA lists each strength of a product separately; these pages share one label.
Prognia shows this product information for reference and learning. It is not treatment advice and can lag behind the official text. Always check the current product information and local protocols before prescribing.
N = Number of patients receiving the treatment. *A patient may have had more than 1 adverse event, including more than 1 adverse event in the same body system. † Vaginal hemorrhage without further diagnosis. ** The combination arm was discontinued due to lack of efficacy benefit at 33 months of follow-up. Certain adverse events and combinations of adverse events were prospectively specified for analysis, based on the known pharmacologic properties and side effect profiles of the two drugs (see the following table).
Number (%) of Patients with Pre-Specified Adverse Event in the Anastrozole Adjuvant Tr
