Case Presentation:

GIST

9th Annual Clinical Cancer Update Conference

Squaw Creek, North Lake Tahoe

January 2010

Anne Espinoza, M.D.

Hematology/Oncology Fellow

University of California, San Francisco

Initial Presentation

• 73 y/o previously healthy F with 3 month

history of abdominal pain radiating to left

shoulder

• associated symptoms: early satiety, bloating

• eating well, no weight loss, denies n/v

• no evidence of GI bleed

• Patient evaluated by her PMD:

• labs, abdomen/pelvis CT ordered

Initial Work-Up

• Labs – normal CBC, Cr, LFTs

• Abdominal/Pelvis CT

• 16.4 x 9.2 cm mass in LUQ located on

anterolateral surface of gastric body

• central necrosis

• no evidence of metastatic disease

Abdomen/Pelvis CT

CT-guided biopsy• moderately cellular proliferation

of fusiform spindle cells in whorls and short intersecting fascicles

• estimated mitotic activity• 10mf/50hpf

• immunohistochemical stains• CD 117 POSITIVE

• CD 34 POSITIVE

• negative:• S-100, muscle specific actin,

desmin, keratin, EMA, mucin

DIAGNOSIS: GASTROINTESTINAL STROMAL TUMOR (GIST)

Additional Work-Up

• Endoscopic Ultrasound

• 18 x 8 cm gastric mass, subepithelial

• arising from proximal inferior stomach

• location: 4cm distal to GE jxn with direct

invasion of stomach over 12 x 7 cm area

• no evidence of associated lymphadenopathy

Additional Work-Up

• PET/CT

• LUQ mass markedly

FDG-avid (SUV 14.7)

• hypermetabolic lesion

in liver not seen on

previous CT scan

QUESTION #1

• What would you recommend as the first

step in management?

1. surgical resection

2. neoadjuvant imatinib with plan for future

resection

3. imatinib with no plans for resection

Initial Treatment

• Decision made to start cytoreductive

treatment with imatinib given the extent of

operation that would be necessary.

QUESTION #2

• Would you perform a mutational analysis

prior to starting imatinib?

1. YES

2. NO

Initial Treatment

• Patient started on imatinib 400 mg daily

• After initiation of imatinib, patient

developed significant skin toxicity (diffuse

macular papular rash)

• imatinib held briefly, then dose reduced to 200

mg daily

• skin toxicity resolved

• follow-up imaging showed no response to

treatment

QUESTION #3

• What would you do now, given lack of

response with low-dose imatinib?

1. no further therapy

2. increase imatinib back to 400 mg daily

3. change to sunitinib

4. start chemotherapy

5. proceed to surgical resection

Continued Therapy

• Imatinib increased back to 400 mg daily

• no recurrent skin toxicity

• Follow-up PET/CT scan showed

significant response to therapy:

• decreased size of primary and liver lesion

• decreased metabolic activity of both lesions

Imaging: baseline & post-imatinib

BASELINE CT CT post-imatinib

Imaging: baseline & post-imatinib

BASELINE PET/CT PET/CT post-imatinib

Continued Therapy

• Patient continued on imatinib at 400 mg

daily for approximately six months

• At six months, imaging showed plateau in

response

QUESTION #4

• What would you do now that patient has had a plateau in response?

1. continue current dose imatinib

2. increase imatinib to 800 mg daily

3. change to sunitinib

4. attempt surgical resection of primary lesion with hepatic metastasectomy or RFA to liver lesion

Surgical Resection

• Patient taken to OR I she underwent:

• subtotal gastrectomy

• partial hepatectomy

Pathologic Findings

15.5 x 5.9 x 6.9 cm mass arising from gastric

wall with internal cystic degeneration

Pathologic Findings

specimens from liver resection showing significant necrosis

(imatinib treatment effect)

20X 200X

Pathologic Findings

area of viable GIST CD 117 stain

QUESTION #5

• What would your plan be for post-

resection treatment/surveillance?

1. surveillance imaging (PET/CT or CT), no

further therapy unless recurrent disease

2. adjuvant imatinib therapy

QUESTION #6

• How long of a treatment course with

adjuvant imatinib would you recommend?

1. six months

2. one year

3. two years

4. indefinite therapy

THANK YOU!