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Radiation Oncology Factoids > DCIS and LCIS > Flashcards

DCIS and LCIS Flashcards

1
Q

What % of all breast malignancies are DCIS?

A

20%

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2
Q

What are the 5 most common histologic subtypes of DCIS?

A

Cribiform, comedo, papillary, medullary, solid

“C2PMS”

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3
Q

Which DCIS subtypes have the worst 2 prognoses?

A

Comedo is the worst

Solid is the second worst

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4
Q

What percentage of DCIS are ER+?

A

75-85% of DCIS are ER+

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5
Q

What is the most common clinical presentation of DCIS?

A

Microcalcifications on a mammogram

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6
Q

What is the most common clinical presentation of LCIS?

A

Usually incidental finding, no mammographic or clinical abnormalities

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7
Q

What percentage of DCIS will progress to invasive disease if left untreated?

A

15-50%, difficult to determine

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8
Q

What is the risk of a patient with LCIS to be diagnosed with invasive breast cancer by 10yrs?

A

7% risk at 10 years but risk is equal in both breasts

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9
Q

What % of patients with LCIS that progress to invasive disease will have invasive lobular carcinoma?

A

Only 25-50% of LCIS patients that progress will have ILC

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10
Q

Which LCIS subtype has the worst prognosis?

A

Pleomorphic LCIS has the worst prognosis

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11
Q

What is the T-stage for DCIS?

A

Tis

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12
Q

What is the definition of DCIS with microinvasion?

A

Invasion <1mm in size, LN Bx is indicated and are found to be positive 4%-8% of the time

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13
Q

What is the treatment paradigm for unifocal DCIS?

A

Lumpectomy + RT +/- tamoxifen
Lumpectomy alone +/- tamoxifen
Mastectomy + SLNBx

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14
Q

Is axillary SLNBx indicated for DCIS?

A

No, but consider if patient undergoing mastectomy or if lumpectomy location may compromise future SLNBx

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15
Q

For a patient with DCIS, what is the rate of LR after mastectomy alone?

A

1-5% at 10 years

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16
Q

What are considered adequate surgical margins in patients receiving breast conservation surgery for DCIS?

A

2mm for patients undergoing postop RT

3mm if no postop RT

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17
Q

Contraindications for BCT for DCIS?

A

Multicentric disease, persistently +margins, cosmetic limitations, inability to get RT (pregnancy, prior RT)

18
Q

Is there a benefit of mastectomy over BCT for DCIS?

A

Undetermined. No prostpective study

19
Q

What is the impact of post-lumpectomy RT on patients with DCIS based on ipsilateral breast tumor recurrence and overall survival?

A

PORT reduces LR by 50-85% but does not benefit OS

20
Q

What are 4 prospective studies that support the addition of RT after lumpectomy?

A

NSABP B-17
EORTC 10853
UKCCCR
SweDCIS

21
Q

Treatment arms and invasive/noninvasive LR outcomes in NSABP B17 and EORTC 10853

A

B17: 818 DCIS pts w/ lumpectomy, neg margins, randomized to RT 50Gy/25fx or no RT; RT reduced LF from 31% to 18%, half of recurrences were invasive

EORTC: 1010 DCIS pts treated with lumpectomy, neg margins, randomized to RT 50Gy/25fx or no RT; RT reduced LF from 31% to 18%, half of recurrences were invasive

22
Q

Traditional target, dose and fractionation for PORT for DCIS?

A

Whole breast 50 Gy in 25 fx

23
Q

Could hypofractionated RT to the whole breast be considered for DCIS?

A

Yes although RCTs for hypofractionation in breast cancer excluded women with DCIS

24
Q

Could APBI be considered for DCIS?

A

Yes - ASTRO consensus statement has low-risk DCIS as suitable for APBI. NSABP B39/RTOG 0413 assessing APBI includes patients with DCIS in addition to early stage invasive breast cancers

25
Q

Is there a benefit to tamoxifen for patients with ER+ DCIS?

A

Yes. NSABP B24 and UKCCCR studies both demonstrate improved incidence of breast events with tamoxifen (NSABP 8.2% vs. 13.4%; HR 0.49) (UKCCCR 12yr ovrall breast events HR 0.71)

26
Q

Is there evidence supporting the use of AIs for DCIS?

A

Yes. NSABP B35 and IBIS-III included tamoxifen or anastrozole in DCIS patients after lumpectomy and RT. B35 reported longer breast cancer free interval with anastrozole in women younger than 60y

27
Q

Is there a role for trastuzumab for DCIS?

A

Not currently. NSABP B43 is evaluating 2 cycles of concurrent trastuzumab with whole breast RT after lumpectomy for DCIS

28
Q

How does adjuvant tamoxifen effect contralateral breast tumor recurrence in patients with DCIS?

A

NSABP B24 showed significant reduction in CBTR as 1st site of recurrence from 4.9% to 2.3% at 7 years

29
Q

For ER+ DCIS, does RT add benefit beyond adjuvant tamoxifen?

A

Yes. UKCCCR was a 2x2 study that demonstrated reduced IBTR in women given RT and tamoxifen (6% vs. 18%)

30
Q

What are risk factors for LR in patients with DCIS?

A

Decreased margin width (most important), increased tumor size, high grade, young age, postmenopausal status, comedonecrosis, multifocality

31
Q

What is the purpose of the Van Nuys Prognostic Classification system?

A

To identify DCIS patients who are at low risk for recurrence after RT alone. Developed from retrospective data and not validated with prospective studies

32
Q

Do all DCIS patients require postop RT?

A

No. Some low-risk can be observed - grade 1-2 DCIS, no larger than 2.5 cm, margins of at least 3mm
ECOG 5194 and RTOG 9804 both evaluate the omission of RT. 5194 showed 12 yr ipsilateral breast event rate 14.6% for G1-2, 24.6% for G3. 9804 showed 6.7% 7 year LF rate.

33
Q

What is the treatment paradigm for LCIS?

A

Observation following lumpectomy for pure LCIS

34
Q

What are options to reduce risk of developing invasive cancer in patients with LCIS?

A 
Antiestrogen therapy (tamoxifen or raloxifene) - NSABP P1 trial
Bilateral mastectomy
35
Q

What should follow if LCIS detected on percutaneous core needle biopsy?

A

Surgical excision to confirm pure LCIS

36
Q

If lumpectomy has invasive cancer and LCIS, can they still get BCT?

A

Yes. BCT is appropriate even with coexisting LCIS without special effort needed.

37
Q

What is the benefit of tamoxifen in patients with LCIS?

A

Halves the risk for invasive recurrence in either breast?

38
Q

What is the most common contraindication for adjuvant tamoxifen therapy?

A

History of stroke or other coagulopathy

39
Q

What is recommended follow up schedule after treatment for DCIS

A

interval H&P exam q6-12m with annual bilateral mammograms

40
Q

What is recommended observation strategy for a patient with LCIS?

A

H&P q6-12mo with annual bilateral mammogram

41
Q

What is the role of MRI screening in patients with previous LCIS or DCIS?

A

MRI indicated if there is a >20% chance for 2nd primary breast cancer based mostly on family history

Radiation Oncology Factoids (44 decks)

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