def get_y_true_survtime_censored(survival_dataframe):
    """
    From dataframe, select only event month and censoring information
    :param survival_dataframe: dataframe that contains many information (output of create_survival_result_dataframe)
    :return: pandas Dataframe with two columns: 'event_month', 'is_censored'
    """
    y_true = survival_dataframe[['event_month', 'is_censored']]
    return y_true