ACCELERATED PARTIAL BREAST IRRADIATION DR BHARTI DEVNANI

MODERATOR:- DR ANJALI K PAHUJA

TREATMENT EVOLUTION

Radiacal Mastectomy

Modified radical mastectomy

Breast conservation therapy

15% to 30% of patients who undergo lumpectomy do not receive radiation therapy

WHY…

Commitment to the 6- 7 week course of adjuvant conventional RT

Cost Distance from the radiation therapy

facility Lack of transportation Lack of social support structure Poor ambulatory status of the patient Physician bias Patient age Fear of radiation treatment

‘ can similar rates of local control be achieved with radiation therapy delivered only to the area at highest risk for recurrence?’ If so, radiation could be delivered in a significantly shortened period

RATIONALE

44% to 86% of local recurrence occurs close to the tumor bed.

Ipsilateral breast recurrences in areas other than the tumor bed occurred rarely in 3% to 4% of the cases.

(similar to the recurrence of contra-lateral second primary breast cancer)

PATIENT SELECTION

INDICATIONS

All invasive carcinomas +

DCIS

ER negative tumors also

included

TECHNIQUES OF APBI

Interstitial Brachytherapy Intracavitory Brachytherapy EXRT IORT Permanent seeds Accu boost

MULTI-CATHETER INTERSTITIAL BRACHYTHERAPY

ADVANTAGES

Longest follow-up.

Better control and tailoring of radiation-dose delivery to variations in lumpectomy cavity, shape, or location within the breast.

Limits toxicity to healthy tissue while delivering the maximum dose to at-risk tissue.

Critical structures can be avoided by differential loading of the catheters

RESULTS

GEC-ESTRO

GEC-ESTRO

WBI(50 Gy/ 25#)

Interstitial brachytherapy32 Gy in 8 fractions HDR,30 Gy in 7 fractions HDR,50 Gy PDR

>40 years,Stages 0-II (T 3 cm),DCIS or invasiveadenocarcinomaNode negative or withmicro-metastasisMargin 2 mm

LIMITATIONS

Considerable training and experience

Appearance and patient acceptance of multiple catheter implants in the breast

high skin dose: great care is required to ensure adequate source-to-skin distance in patients treated with brachytherapy

Therefore, may not be a viable treatment option for patients with superficial tumors or small breasts

INTRACAVITORY BRACHYTHERAPY

Balloon based brachytherapy include:

Mammosite

Axxent electronic brachytherapy

Contura

MAMMOSITE BRACHYTHERAPY SYSTEM

STRUCTURE Silicone balloon

Double-lumen catheter (15 cm length and 6 mm in diameter)

Inflation channel:- saline solution mixed with a small amount of contrast material to aid visualization.

Source channel:- for passage of an Ir-192 high dose rate (HDR) brachytherapy source.

Source channel runs centrally through the length of the balloon.

after lumpectomy, the catheter is placed in the breast cavity either during the lumpectomy procedure or later through a closed technique

balloon is inflated with 35 to 70 mL of saline mixed with a small amount of contrast material, depending on the size of the lumpectomy cavity

CT imaging to assess the adequate placement of the device

An Ir-192 radioactive source, connected to a computer-controlled HDR remote after-loader, is inserted through the catheter into the balloon to deliver the prescription radiation dose

QUALITY OF THE IMPLANT

Ballon Conformance: assessed by quantifying the volume of the PTV that is filled by air or seroma fluid.

Less than 10% of the PTV should be composed of fluid or air.

Too

much air

Large serom

a

Minimum balloon-to-skin distance: for good cosmesis

Min: 5 mm Recommended :7mm Anthracyclin based chemo :10 mm

Close to the skin

Symmetry Essential for adequate dosimetry. A non-symmetrical implant can result in

dose inhomogeneity in the surrounding tissues since the MSB device contains a single, central source channel that does not allow for shaping of the radiation isodose curves in the direction perpendicular to the central channel

Asymmetrical

DOSE

34 Gy over 10 fractions (3.4 Gy per fraction, twice daily )

Prescription point is 1 cm from the balloon surface

Minimum 6 hours gap

D 90> 90% V150< 50cc V200< 20 cc HI >0.75 Skin dose Max <145%

Limitations Not suitable in patients with small breast .

Tumors located in the upper-inner quadrant.

Irregular cavity . (Requirement for skin-to-cavity distances:-

not met)

Advantages

more user-friendly technique for brachytherapy

easily reproducible

MammoSite Multi-lumen (4 lumen) device

RESULTS OF MAMMOSITE

Balloon based brachytherapy include:

Mammosite

Axxent electronic brachytherapy

Contura

AXXENT ELECTRONIC BRACHYTHERAPY

Ballon is radiolucent :- no need of contrastHoles in the ballonThird port for drainage of seroma fluid or air surrounding the cavity.

Miniature X-ray source

eB controller

•Portable unit

•Digital touch-screen for the Physician and Physicistto input treatment data and monitor treatment progress.

ADVANTAGES

Specifically shielded radiation room or an HDR afterloader unit are not required.

This reduces costs and allows for portability of the system, which can lead to greater access for patients particularly in more remote or rural locations.

Can be used intraoperatively

Electronic 50 Kv x-ray source Low energy spectrum that results in more rapid

dose falloff with depth in tissue. Radiobiologic effect (RBE) for low-energy

photons is higher on the order of 1.2-2 (53e55). This has currently not been taken into account

in the prescribed dose for EBB, which uses the same prescription of 34.0 Gy in 10 fractions as used with192Ir.

Dose to structures proximal to the point(1 cm) is higher and the dose to structures beyond this point is lower with EBB

Careful clinical evaluation is needed to determine the clinical impact of these factors with respect to late tissue affects and cosmesis.

CONTURA

Has multiple lumens for passage of an Ir-192 HDR source.

In addition to a central lumen, the Contura balloon has four surrounding channels to accommodate the HDR source.

Additional source positions allows increased dose flexibility compared with a single-catheter approach.

Reduce the dose to normal tissues (chest wall and skin) better protection of organs at risk such as the heart and lungs.

Possible to account for asymmetric balloon implant with respect to the central channel.

vacuum port to remove fluid or air around the lumpectomy cavity.

HYBRID BRACHYTHERAPY DEVICES

Struts Adjusted Volume Implant (SAVI) ClearPath

INTERSTITIAL BRACHYTHERAPY(VERSATILITY AND DOSIMETRIC CONFORMITY)

BALLOON BRACHYTHERAPY(CONVENIENCE OF A SINGLE

ENTRY DEVICE)

HYBRID DEVICES

ADVANTAGES

Ability to sculpt the radiation dose based on patient’ s anatomy.

Might permit the treatment of patients who were previously ineligible for other methods.

Reduce the dose to skin and chest wall Better protection of critical organs at risk

STRUT ADJUSTED VOLUME IMPLANT (SAVI)

Consists of a central strut

Sorrounded by 6,8 or 10 peripheral struts

Can be differentially loaded with HDR source

Insertion done in collapsed form through an incision (LA ;USG guided)

Then expanded to fit the cavity

CT aquired (verification and planning)

CLEARPATH

Contains six outer expandable plastic tubes to displace the tissue

Central catheter surrounded by six additional catheters that allow the passage of an HDR iridium-192 source

The radiation source is not in direct contact with the breast tissue

EXTERNAL BEAM RADIOTHERAPY3D-CRT/ IMRT

ADVANTAGES

Non-invasive (complications of surgery like seroma and infection can be avoided)

Widespread availability

Technically less demanding

Treatment results with external beam may be more uniform between radiation oncologists

Greater dose homogeneity

Acceptable cosmesis

3.85 Gy twice daily (separated by at least 6 hours) to a total dose of 38.5 Gy delivered within 1 week

NSABP B-39 TRIAL

RAPID TRIAL-RANDOMIZED TRIAL OF ACCELERATED PARTIAL BREAST IRRADIATION (2006)

2128 patients

Hypofrationated WBI

(42.5 Gy/ 16#/22 days)

38.5 Gy/10#/5-8

days

Large breasted patient :- 50 Gy/25#Boost allowed :- 10 Gy/5#2014- primary completion

40 years,T < 3 cm,DCIS or invasive carcinoma,Node negative,Margin negative,No BRCA1 or 2

STANDARD OR HYPOFRACTIONATED RADIOTHERAPY VERSUS APBI FOR BREAST CANCER (SHARE TRIAL)

SHARE

WBI

50 Gy+ 16 Gy boost

Hypo42.5 Gy/16# or 40 Gy/15#

APBI

40 Gy/10#

EXRT (IMRT)

UK INTENSITY MODULATED AND PARTIAL ORGAN RADIOTHERAPY (IMPORT- LOW )

IORT

ADVANTAGES Accurate dose delivery Direct visualization of the tumor bed

Better protection of healthy tissues by moving them away from the path of the radiation beam.

Eliminates the risk of geographical miss

Oxygen effect :-Rich vascularization in tissues with aerobic metabolism, which makes them more sensitive to the action of the radiation .

Single intraoperative application eliminates the risk of patients not completing the prescribed course of breast radiotherapy.

Does not require a specially designed operating room

TARGIT

P= 0.41(NS)

N0 difference in local recurrence

Radiotherapytoxicity was lower in the targeted intraoperative radiotherapy group (sixpatients [0·5%]) than in the external beam radiotherapy group (23 patients [2·1%]; p=0·002).

MOBETRON (ELECTRONS)

• Control consolewhich operates the accelerator during radiation treatment delivery

• Modulator houses the electronic systems of the accelerator and energizes the accelerator to produce the electron

• Therapy module houses the accelerator guide and control systems that generate and deliver radiation

• 4 MeV, 6 MeV, 9 MeV and 12 MeV with therapeutic ranges up to 4 cm

NOVAC-7 (ELECTRONS)• delivers electrons with the use of a mobile dedicated linear accelerator• its radiating head can be movedby an articulated arm that can work in an existing operating room• It delivers electron beams at fourdifferent nominal energies (3, 5, 7 and 9 Mev)• Beam are collimated by means of a hard docking system, consisting of cylindrical perspex applicators availablein different diameters (4 to 10 cm) and angles of the head (perpendicular or oblique 15° to 45°)

NOVEL METHODS

PERMANENT BREAST SEED IMPLANT

Percutaneous insertion of radioactive seeds (palladium-103 ) under US guidance

Use of LDR sources has the potential for improving the therapeutic ratio

A preplan is generated with optimal seed position and spacing to deliver the prescribed dose of 90 Gy to cover the lumpectomy cavity with a 1.5-cm margin.

Using a grid template 103Pd seeds are placed according to the preplan needle and seed distribution.

NONINVASIVE IMAGE-GUIDED BREAST BRACHYTHERAPY(ACCUBOOST)

Breast immobilization Moderate compression between two mammography paddles. This

technique achieved stable position of the breast and lumpectomy cavity for imaging and treatment.

Imaging is then performed using 30-kVp X-rays, similar to mammography, in the immobilized position and in the treatment plane.

Imaged-guided target delineation The lumpectomy cavity is delineated, usually with the assistance

of radiopaque clips placed at the time of lumpectomy. Using a target localization grid, the appropriate applicator size

and position are selected to cover the lumpectomy cavity with an appropriately margin.

The selected tungsten alloy applicators are mounted on the mammography paddles centered on the target.

Treatment with collimated photon emission using 192 Ir HDR brachytherapy

Treatment is then delivered using directed photons in a parallel-opposed fashion from an 192Ir HDR source.

The process is then repeated along a second intersecting orthogonal axis in a sequential manner.

The orthogonal axes are usually oriented in craniocaudal and mediolateral directions so that presurgical mammography can be used to further assist and ensure appropriate target coverage

In about 5-8 years, the ongoing studies will hopefully answer the questions related to patient selection, long-term outcome, and toxicity of the different techniques.

A modest reduction in initial treatment efficacy cannot be justified in patients with early breast cancer, who have an excellent prognosis with standard BCT including WBI.

For the coming years, patients should be carefully selected for APBI and closely followed with accurate documentation of any occurring events.

THANK YOU