diff --git a/query_server/query_operations.py b/query_server/query_operations.py
index b746fbe..5f8253c 100644
--- a/query_server/query_operations.py
+++ b/query_server/query_operations.py
@@ -76,12 +76,13 @@ def add_or_increment(dict, key):
     else:
         dict[key] = 1
 
-def get_summary_stats(donors, primary_diagnoses, headers):
+def get_summary_stats(donors, primary_sites, treatments):
     # Perform (and cache) summary statistics
     age_at_diagnosis = {}
     donors_by_id = {}
     primary_site_count = {}
     patients_per_cohort = {}
+    treatment_type_count = {}
     for donor in donors:
         # A donor's date of birth is defined as the (negative) interval between actual DOB and the date of first diagnosis
         # So we just use that info
@@ -97,35 +98,19 @@ def get_summary_stats(donors, primary_diagnoses, headers):
                 add_or_increment(age_at_diagnosis, f'{age}-{age+9} Years')
 
         program_id = donor['program_id']
-        if program_id in patients_per_cohort:
-            patients_per_cohort[program_id] += 1
-        elif program_id is not None:
-            patients_per_cohort[program_id] = 1
-
-    # primary sites
-    for primary_diagnosis in primary_diagnoses:
-        primary_site = primary_diagnosis['primary_site']
-        if primary_site in primary_site_count:
-            primary_site_count[primary_site] += 1
-        else:
-            primary_site_count[primary_site] = 1
-
-    # Treatment types
-    # http://candig.docker.internal:8008/v3/authorized/treatments/
-    treatments = requests.get(f"{config.KATSU_URL}/v3/authorized/treatments/?page_size={PAGE_SIZE}",
-        headers=headers)
-    treatments = safe_get_request_json(treatments, 'Katsu treatments')['items']
-    treatment_type_count = {}
-    for treatment in treatments:
-        if (treatment["submitter_donor_id"] in donors_by_id and
-            "treatment_type" in treatment and
-            treatment["treatment_type"] is not None):
-            try:
-                for treatment_type in treatment["treatment_type"]:
-                    add_or_increment(treatment_type_count, treatment_type)
-            except TypeError as e:
-                logger.error(f"Could not grab summary treatment stats: {e}")
-                pass
+        add_or_increment(patients_per_cohort, program_id)
+
+        # primary sites
+        if donor['submitter_donor_id'] in primary_sites:
+            if primary_sites[donor['submitter_donor_id']] is not None:
+                for primary_site in primary_sites[donor['submitter_donor_id']]:
+                    add_or_increment(primary_site_count, str(primary_site))
+            else:
+                add_or_increment(primary_site_count, 'None')
+
+        if donor['submitter_donor_id'] in treatments and treatments[donor['submitter_donor_id']] is not None:
+            for treatment_type in treatments[donor['submitter_donor_id']]:
+                add_or_increment(treatment_type_count, treatment_type)
 
     return {
         'age_at_diagnosis': age_at_diagnosis,
@@ -226,44 +211,44 @@ def query(treatment="", primary_site="", drug_name="", systemic_therapy_type="",
     # We're grabbing (and storing in memory) all the donor data in Katsu with the below request
 
     # Query the appropriate Katsu endpoint
-    params = { 'page_size': PAGE_SIZE }
-    url = f"{config.KATSU_URL}/v3/authorized/donors/"
-    r = safe_get_request_json(requests.get(f"{url}?{urllib.parse.urlencode(params, True)}",
-        # Reuse their bearer token
-        headers=headers), 'Katsu Donors')
-    donors = r['items']
+    url = f"{config.KATSU_URL}/v3/authorized/query/"
+    headers = {}
+    for k in request.headers.keys():
+        headers[k] = request.headers[k]
+    headers["X-Service-Token"] = config.SERVICE_TOKEN
+
+    param_mapping = [
+        (treatment, "treatment_type"),
+        (primary_site, "primary_site"),
+        (drug_name, "systemic_therapy_drug_name"),
+        (systemic_therapy_type, "systemic_therapy_type"),
+        (exclude_cohorts, "exclude_cohorts")
+    ]
+    params = {}
+    for param in param_mapping:
+        if param[0] == "" or param[0] == []:
+            continue
+        params[param[1]] = param[0]
+
+    full_url = f"{url}?{urllib.parse.urlencode(params, doseq=True)}"
+    donors = safe_get_request_json(requests.get(full_url, headers=headers), 'Katsu explorer donors')['items']
 
     # Filter on excluded cohorts
     donors = [donor for donor in donors if donor['program_id'] not in exclude_cohorts]
 
-    # Will need to look into how to go about this -- ideally we implement this into the SQL in Katsu's side
-    filters = [
-        (treatment, f"{config.KATSU_URL}/v3/authorized/treatments/", 'treatment_type', None)
-    ]
-    if type(systemic_therapy_type) is list:
-        for this_type in systemic_therapy_type:
-            filters.append((drug_name, f"{config.KATSU_URL}/v3/authorized/systemic_therapies/", 'drug_name', this_type))
-    else:
-        filters.append((drug_name, f"{config.KATSU_URL}/v3/authorized/systemic_therapies/", 'drug_name', None))
-
-    for (this_filter, url, param_name, therapy_type) in filters:
-        if this_filter != "":
-            permissible_donors, _ = get_donors_from_katsu(
-                url,
-                param_name,
-                this_filter,
-                headers,
-                therapy_type
-            )
-            donors = [donor for donor in donors if donor['submitter_donor_id'] in permissible_donors]
-    permissible_donors, primary_diagnoses = get_donors_from_katsu(
-        f"{config.KATSU_URL}/v3/authorized/primary_diagnoses/",
-        'primary_site',
-        primary_site if primary_site != "" else [],
-        headers,
-        keep_all=True
-    )
-    donors = [donor for donor in donors if donor['submitter_donor_id'] in permissible_donors]
+    # Note: We get three extra things from /authorized/query that aren't part of the Donors object:
+    # 1) submitter_sample_ids
+    # 2) primary_site
+    # 3) treatment_type
+    # These are used to build the summary information without needing to re-query Katsu
+    # For the purposes of the return value, let's remove all three of these into their own variables
+    summary_info = {}
+    summary_headers = ['submitter_sample_ids', 'primary_site', 'treatment_type']
+    for header in summary_headers:
+        summary_info[header] = {}
+        for donor in donors:
+            summary_info[header][donor['submitter_donor_id']] = donor[header]
+            del donor[header]
 
     # Now we combine this with HTSGet, if any
     genomic_query = []
@@ -327,12 +312,8 @@ def query(treatment="", primary_site="", drug_name="", systemic_therapy_type="",
         except Exception as ex:
             logger.error(f"Error while reading HTSGet response: {ex}")
 
-    # We also need to cut down the list of primary diagnoses based on the filtered list of donors at this point
-    permissible_donors = set([donor['submitter_donor_id'] for donor in donors])
-    primary_diagnoses = [primary_diagnosis for primary_diagnosis in primary_diagnoses if primary_diagnosis['submitter_donor_id'] in permissible_donors]
-
     # TODO: Cache the above list of donor IDs and summary statistics
-    summary_stats = get_summary_stats(donors, primary_diagnoses, headers)
+    summary_stats = get_summary_stats(donors, summary_info['primary_site'], summary_info['treatment_type'])
 
     # Determine which part of the filtered donors to send back
     full_data = {