Use of PET scan in NSCLC our initial experience

USE OF PET SCAN IN NSCLC:
OUR INITIAL EXPERIENCE

WHAT IS PET IMAGING
POSITRON EMISSION TOMOGRAPHY IS AN EXCITING NEW
MODALITY WHERE SHORT LIVED POSITRON EMITTING
ISOTOPES
ARE USED TO IMAGE FUNCTION AND METABOLIC
ACTIVITY OF
DIFFERENT ORGANS AND DISEASE PROCESSES.

EDWARD J HOFFMAN &MICHAEL PHLEPS DEVELOPED THE
FIRST HUMAN PET SCANNER IN 1973 AT WASHINGTON
UNIVERSITY.
PET CENTER AT UNIVERSITY OF PENNYSYLVANIA WAS THE
FIRST CENTER ESTABLISHED IN 1975 AS A RESEARCH FACILITY
FOR STUDY OF HUMAN BRAIN FUNCTION.
SINCE 1991 PET APPLICATION INCREASED &INCLUDED IN
CLINICAL STUDIES

APPLICATION OF PET
ONCOLOGY
 EARLY DETECTION OF
CANCER
 MAPPING EXTENT OF
DISEASE/STAGING.
AS A TOOL IN RT PLANNING.
MONITORING RESPONSE OF
THERAPY
DETECTING RECURRENCES
DIFFERENTIATING
RECURRENCES FROM EDEMA/
NECROSIS.
NON ONCOLOGY
CARDIOLOGY
 NEUROLOGY
INFECTION IMAGING

PET IS MOSTLY USED IN:
LUNG CANCER
 BREAST CANCER
 LYMPHOMA
 MELANOMA
 COLON CANCER
 HEAD AND NECK CANCERS

TREATMENT OF NSCLC DEPENDS ON :
LOCATION OF PRIMARY TUMOR
• EXTENTION OF DISEASE
• PRESENCE OR ABSENCE OF MEDICAL COMORBIDITIES
• ASSESSMENT OF .
- EXTAPULMONARY INTRATHORACIC
METASTASIS.
- EXTRATHORACIC METASTASIS

PET SCAN :INNOVATION IN LUNG
CANCER IMAGING
WHOLE BODY FDG PET SCAN HAS SHOWN
99% SENSITIVITY IN DETECTING PRIMARY TUMOR AT
INITIAL WORK UP FOR NSCLC.
91% SENSITIVITY IS SEEN AT DETECTING MEDIASTINAL
LYMPH NODE PREOPERATIVELY.

OVERVIEW FROM VARIOUS PROSPECTIVE
PERFORMANCE STUDIES
IN ASSESSMENT OF LOCOREGIONAL LYMPH
NODE SPREAD
PET HAS :
NEGATIVE PREDICTIVE VALUE IN EXCLUSION OF
N2 OR N3 DISEASE.
FALSE NEGATIVE RESULTS IN MEDIASTINAL PET
WITH MINIMAL N2 DISEASE.
- FALSE POSITIVE FINDINGS SEEN IN PATIENTS
WITH
INFLAMMATORY NODES.
GRANULOMATOUS DISORDERS.
ISOLATED POSITIVE FINDING NEEDS PATHOLOGIC
VERIFICATON: POSSIBILITY OF FALSE POSITIVE RESULTS.

IN EXTRA THORACIC STAGING PET IS USEFUL ADJUNCT
TO CONVENTIONAL IMAGING
DUE TO ABILITY TO DETECT UNEXPECTED
METASTASIS
CURRENTLY INSUFFICIENT DATAAVAILABLE TO STATE
THAT PET COULD REPLACE STANDARD IMAGING.
IT NOW UNDERGOES VALIDATION IN LARGE SCALE
RANDOMISED PATIENT OUTCOME STUDIES.
MEANWHILE CURRENT RECOMMENDATION FOR USE OF
PET SCAN IN CONTEMPORARY LUNG CANCER IS
PROVIDED.

HIGH RATE OF DETECTION OF UNSUSPECTED DISTANT
METASTASIS BY PET SCAN IN APPARENT STAGE III
NSCLC:IMPLICATIONS FOR RADICAL RADIATION
THERAPY.
PET STAGING IS RECOMMENDED FOR RADICAL RT,
AS HIGHEST YEILD OF UNSUSPECTED DISTANT
METS IS OBSERVED IN STAGE III DISEASE &
ULTIMATELY PATIENT DIE OF DISTANT METASTASIS.
COMPARISON OF PET-STAGED AND
CONVENTIONALLY STAGED COHORTS TREATED .
TWO PROSPECTIVE COHORTS : PET SCAN 80 PTS.
: NON PET SCAN
77 PTS.
30% OF RADICAL RT CANDIDATES BECAME INELIGIBLE
FOR RADICAL RT AS COMPARED WITH THOSE STAGED
CONVENTIONALY.

23% CASES MANAGEMENT STRATEGY CHANGED FROM
RADICAL TO PALLIATIVE INTENT
22% CASES NEW FDG AVID NODES FOUND IN 5 CM OF
PRIMARY TUMOR WERE INCLUDED IN PTV
17-29% CASES POORLY COVERED WITH CT BASED
GEOGRAPHICAL MISS WELL INCLUDED IN PET PLANNING
30-76% CASES INCREASE IN PTV
24-70% CASES REDUCTION IN PTV
( HIGH IMPACT IN PATIENT WITH ATELECTASIS)
THUS RELATIVE CHANGE IN PTV RANGED FROM 0.4 -
1.86

REVIEW LITERATURE :FDG PET IMPACT ON STAGE
& CONTOURED GTV
TNM STAGING CHANGED 8/26 (31%)
METS DISEASE FOUND 2/26 (8%)
GTV CONTOUR CHANGED 14/24 (58%)
GTV VOLUME DECREASE 3/24 (12%)
GTV VOLUME INCREASED 11/24 (46%)
(ADDITIONAL TUMOR DETECTED)
MINIMAL GTV CHANGE 10/24 (42%)

MEAN LUNG DOSE, V20,MEAN ESOPHAGIAL DOSE HAS BEEN
IDENTIFIED
AS PREDICTORS OF NORMAL TISSUE COMPLICATIONS
WHEN GTV DECREASED IN PATIENTS WITH ATELECTASIS
,DOSES OF
NORMAL TISSUES SUCH AS LUNG AND ESOPHAGUS ARE
DECREASED
- THEREBY PROBABILITY OF PNEUMONITIS AND
ESOPHAGITIS IS DECREASED
 WHEN GTV ENLARGED TO INCORPORATE ADDITIONAL PET
DETECTED
TUMOR , THE VALUES OF MEAN LUNG DOSE, V20 & MED
ARE INCREASED
LEADING TO HIGHER COMPLICATIONS PROBABILITIES

MONITORING TREATMENT RESPONSE IN
NSCLC
PET CAN DIFFERENTIATE BETWEEN RECURRENT OR RESIDUAL
TUMOR
AND POST TREATMENT CHANGES
(ALTHOUGH CONVENTIONAL NON INVASIVE MODALITIES SUCH AS
CT OR MRI PROVIDES EXCELLENT MORPHOLOGIC INFORMATION)
USING SUV OF EARLY AND DELAYED IMAGES, RETENTION
INDEX IS
CALCULATED ( RI < 0.1; > 0.1) {SUV=STANDARDISED
UPTAKE VALUE}
 FINAL WEEK OF RT PET IS DONE WITH INTENTION OF
INCREASING
FINAL DOSE (IN PATIENS WHOSE RI REMAINS ELEVATED)
SERIAL IMAGING AT SAME SITES OVER A PERIOD OF MORE
THAN 3 MONTHS
CLARIFY THE EFFICACY OF THIS MODALITY IN THE PROVISION
OF
PROGNOSTIC INFORMATION

DECIDING TREATMENT STRATEGY :
CURATIVE / PALLIATIVE.
IMPROVES VOLUME DELINEATION :
TARGET
NORMAL/CRITICAL ORGAN.
REDUCES RISK OF GEOGRAPHICAL MISS.
DISTINGUISHES TUMOR FROM ATELECTASIS.
 PROGNOSIS / MONITORING TREATMENT
RESPONSE.

Use of PET scan in NSCLC our initial experience

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