You will be shown a paragraph from a biomedical research article. Your task is to extract all drug combinations appearing in a specific sentence within in the paragraph. Each drug combination should be assigned to one of the following three categories:

- POS: Indicates a positive interaction between the drugs in the combination; for instance, drugs that have an additive or synergistic effect.
- NEG: Indicates a negative interaction between the drugs in the combination; for instance, combining these drugs might result in adverse side effects, or might reduce their efficacy.
- COMB: Indicates that the drugs are given in combination, but the type of interaction between the drugs cannot be determined based on the provided context.

Please format your answer as a json array. Each entry in the array should itself be an array formatted as [<drug_1>, <drug_2>, ..., <drug_n>, <category>] where <category> is one of the three categories listed above and <drug_1>, ..., <drug_n> are drug names copied verbatim from the input sentence. Different combinations may involve different numbers of drugs; in other words, the `n` in <drug_n> may vary.

As an example, the following output describes two extracted drug combinations; one between two drugs, and one between three drugs:

[["artesunate", "artemether", "COMB"], ["Nifedipine", "Labetalol", "Prazosin", "POS"]]

The paragraph and specific sentence are below. You should only extract relationships expressed in the specific sentence; the paragraph is provided for context.

In your output, return only the json array and no other text. If no drug combinations appear, return an empty array `[]`.

paragraph: Economic Evaluation of Anastrozole Versus Tamoxifen for Early Stage Breast Cancer in Singapore. In Singapore, breast cancer is the leading female malignancy and its incidence has increased threefold over the past decades. For treatment of postmenopausal, hormone receptor positive early stage breast cancer, tamoxifen or aromatase inhibitors such as anastrozole are prescribed either as first-line therapy or sequentially. Currently, anastrozole is patented with a higher drug cost compared with tamoxifen. Hence , the aim of this study was to conduct an economic evaluation of anastrozole versus tamoxifen in early stage breast cancer . ### methods A Markov model with a lifetime horizon was developed by using results from the Arimidex, tamoxifen, Alone or in Combination trial. Direct medical costs were estimated by billing data obtained via financial electronic databases. Utility scores were elicited from 20 experienced oncology nurses using the visual analogue scale. Cost per quality-adjusted life-years was calculated by using the societal perspective. A discount rate of 3% for both charges (expressed in 2010 Singapore dollars) and benefits was used. ### results At an additional cost of S $17,597, anastrozole treatment resulted in a gain of 0.085 life-year survival and 0.154 quality-adjusted life-year. The incremental cost-effectiveness ratio of anastrozole was S $207,402 per life-year gained and S $114,061 per quality-adjusted life-year gained compared with tamoxifen. ### conclusion This is the first economic evaluation that used 10-year results from the Arimidex, tamoxifen, Alone or in Combination trial and utility elicited from the local population. If the World Health Organization's recommendation of 1 to 3 gross domestic product range is an acceptable threshold, anastrozole is deemed cost-effective compared with tamoxifen in the treatment of early stage breast cancer.

sentence: Hence , the aim of this study was to conduct an economic evaluation of anastrozole versus tamoxifen in early stage breast cancer .
[]