Predictive value of [18F]FDG PET for pathological response of breast cancer to neo-adjuvant chemotherapy

Breast conservation in locally advanced breast cancer in developing countries: wise or waste

Breast conservation as an additional benefit was beyond the initial expectations of the investigators who pioneered neoadjuvant chemotherapy (NACT). In recent years an increasing number of patients with locally advanced breast cancer (LABC) are being treated with NACT, followed by breast conservation surgery with axillary dissection and radiation as a part of the multimodality management. Breast conservation has not been the standard of care for women with LABC, owing to concerns of increased chances of local recurrence, and possible survival disadvantage and psychological trauma from experiencing a recurrence of malignancy. LABC is still a common form of presentation of breast cancer in developing countries. Strict adherence to treatment protocols and regular follow-ups for years may not be practical for a large majority of patients hailing from the regions most affected by LABC. Defaulters often thus have a heavy price to pay. Hence lies the importance of carefully selecting LABC patients for a breast conservation approach from others that would have a higher risk of locoregional recurrence. Can we extrapolate the lessons learnt in early breast cancer to LABC and offer selected patients with LABC breast conservation therapy? Would the local control and survival results with conservative therapy be comparable to those obtained using mastectomy, or does the increased tumor burden in LABC necessitate ablative surgery in all women? This review aims to address these important questions.

Bone metastases in patients with metastatic breast cancer: morphologic and metabolic monitoring of response to systemic therapy with integrated PET/CT

PURPOSE

To retrospectively compare morphologic and metabolic changes in bone metastases in response to systemic therapy in patients with metastatic breast cancer (MBC) with integrated positron emission tomography (PET)/computed tomography (CT).

MATERIALS AND METHODS

The institutional review board waived the requirement for informed consent and approved this HIPAA-compliant study. A retrospective analysis was performed with 102 women (mean age, 55 years) with MBC who received systemic treatment. All patients underwent integrated PET/CT before and after treatment. Two reviewers analyzed the images in consensus. Morphologic changes, including morphologic patterns, and lesion attenuation were evaluated. Standardized uptake value (SUV) and total lesion glycolysis (TLG) were analyzed to evaluate metabolic changes. Uni- and multivariate analyses were performed to identify factors that enabled response duration (RD) to be predicted.

RESULTS

At baseline, the morphologic patterns of the target lesions were lytic (n = 33), sclerotic (n = 22), mixed (n = 42), and unclassified (n = 5). Progression of sclerotic change after treatment was identified in 49 patients (48%). After treatment, the mean attenuation of the lesion increased, whereas the mean SUV and TLG decreased. Increases in attenuation correlated significantly with decreases in SUV (r = -0.510, P < .001) and TLG (r = -0.491, P < . 001). Univariate analysis revealed that the increase in attenuation and the decrease in SUV were potential predictors of RD. Multivariate analysis revealed that an increase in the change in SUV was a significant predictor of RD (relative risk, 2.4; P = .003).

CONCLUSION

A decrease in SUV after treatment was an independent predictor of RD in patients with MBC who had bone metastases.

FDG PET, PET/CT, and breast cancer imaging

Currently, the clinical role of positron emission tomography (PET) and PET/computed tomography (CT) in patients with breast cancer is to provide additional information in select scenarios in which results of conventional imaging are indeterminate or of limited utility. There is currently no clinical role for fluorodeoxyglucose (FDG) PET in detection of breast cancer or evaluation of axillary lymph nodes, but these are areas of active research. FDG PET is complementary to conventional staging procedures and should not be a replacement for either bone scintigraphy or diagnostic CT. FDG PET and PET/CT have been shown to be particularly useful in the restaging of breast cancer, in evaluation of response to therapy, and as a problem-solving method when results of conventional imaging are equivocal. In these situations, FDG PET often demonstrates locoregional or unsuspected distant disease that affects management. PET has demonstrated a particular capability for evaluation of chemotherapy response in both patients with locally advanced breast carcinoma and those with metastatic disease.

FDG-PET Evaluation of Response to Treatment

This article discusses evaluating response after and during therapy in various settings and for the types of cancers for which ample evidence demonstrates that PET imaging with flourodeoxyglucose provides a valuable surrogate for response to therapy. It also briefly discusses pitfalls in obtaining an optimal assessment of response and issues that need further attention for this modality to become established as an independent predictor of response to anticancer therapy.

PET/CT in oncology: for which tumours is it the reference standard?

Positron emission tomography (PET)/computed tomography (CT) has a growing role in the imaging of many cancers. As our experience has grown over the past number of years so has our understanding for which cancers it is particularly useful. The value of PET/CT at each stage of the cancer journey is different for each cancer. This review attempts to tease out the role of PET/CT in the common cancers with particular emphasis on where it is the imaging investigation of choice.

Current Status of Breast MR Imaging Part 2. Clinical Applications

Magnetic resonance (MR) imaging is emerging as the most sensitive modality that is currently available for the detection of primary or recurrent breast cancer. Although this technique has been shown to be an extremely powerful diagnostic tool, it is still relatively rarely used in clinical practice, as compared with other applications of MR imaging such as for musculoskeletal or brain and spine imaging. This is the second of a two-part series on the current status of breast MR. Part two provides an overview of the use of breast MR imaging in clinical patient care, the body of evidence that supports its use. A discussion is provided on the many controversies that exist regarding breast MR imaging for preoperative staging and for screening.

A randomized phase-III trial of docetaxel/capecitabine versus doxorubicin/cyclophosphamide as primary chemotherapy for patients with stage II/III breast cancer

We aimed to determine the efficacies of a non-anthracycline-containing regimen, docetaxel/capecitabine (TX), in comparison with an anthracycline-containing regimen, doxorubicin/cyclophosphamide (AC), as primary chemotherapy for node-positive early stage breast cancer. In this phase-III single center randomized study, we randomized 209 women with axillary node positive, stage II/III breast cancer to receive four cycles of either TX or AC followed by surgery and cross-over to the other treatment as an adjuvant therapy. The primary endpoint was tumor pathologic complete response (pCR). Clinical response rates, toxicity profiles, disease free survival (DFS), and overall survival were secondary objectives. In total, 204 patients had clinical and radiological evaluation of response, and underwent surgery. Compared with AC, TX increased pCR in primary tumors (21% vs. 10%, respectively, P = 0.024) and clinical response (84% vs. 65%, P = 0.003). TX was associated with less nausea and vomiting, but more stomatitis, diarrhea, myalgia, and skin/nail changes than AC. With a median follow-up of 37 months, there was no significant difference in DFS by treatment groups (P = 0.932). Fewer patients developed recurrence who achieved pCR in lymph node (LN) (P = 0.025; hazard ratio, 0.189; 95% CI, 0.044-0.815) in the multivariate analysis. TX showed superior efficacies to AC with increased pathologic and clinical complete response rates. Although these findings did not translate into a gain in DFS, the patients who achieved pCR in LN developed significantly less recurrence.

[18F]FDG-PET predicts complete pathological response of breast cancer to neoadjuvant chemotherapy

PURPOSE

To evaluate, in breast cancer patients treated by neoadjuvant chemotherapy, the predictive value of reduction in FDG uptake with regard to complete pathological response (pCR).

METHODS

Forty-seven women with non-metastatic, non-inflammatory, large or locally advanced breast cancer were included. Tumour uptake of FDG was evaluated before and after the first course of neoadjuvant chemotherapy. Four indices were used: maximal and average SUV without or with correction by body surface area and glycaemia (SUV(max), SUV(avg), SUV(max-BSA-G) and SUV(avg-BSA-G), respectively). The predictive value of reduction in FDG uptake with respect to pCR was studied by logistic regression analysis. Relationships between baseline [(18)F]FDG uptake and prognostic parameters were assessed.

RESULTS

The relative decrease in FDG uptake (DeltaSUV) after the first course of neoadjuvant chemotherapy was significantly greater in the pCR group than in the non-pCR group (p < 0.000066). The four FDG uptake indices were all strongly correlated with each other. A decrease in SUV(max-BSA-G) of 85.4% +/- 21.9% was found in pCR patients, versus 22.6% +/- 36.6% in non-pCR patients. DeltaSUV(max-BSA-G) <-60% predicted the pCR with an accuracy of 87% and DeltaSUVs were found to be only factors predictive of the pCR at multivariate analysis. An elevated baseline SUV was associated with high mitotic activity (p < 0.0016), tumour grading (p < 0.004), high nuclear pleomorphism score (p < 0.03) and negative hormonal receptor status (p < 0.005).

CONCLUSION

In breast cancer patients, after only one course of neoadjuvant chemotherapy the reduction in FDG uptake is an early and powerful predictor of pCR.

Positron emission tomography in oncology: a review

Positron emission tomography is an evolving imaging tool that is becoming increasingly available for use in clinical practice. This overview will look at the current evidence for the use of positron emission tomography in imaging different tumour types and the different radiotracers that are either available or being evaluated in an investigational setting.

Predicting response to breast cancer neoadjuvant chemotherapy using diffuse optical spectroscopy

Diffuse optical spectroscopy (DOS) and imaging are emerging diagnostic techniques that quantitatively measure the concentration of deoxy-hemoglobin (ctHHb), oxy-hemoglobin (ctO(2)Hb), water (ctH(2)O), and lipid in cm-thick tissues. In early-stage clinical studies, diffuse optical imaging and DOS have been used to characterize breast tumor biochemical composition and monitor therapeutic response in stage II/III neoadjuvant chemotherapy patients. We investigated whether DOS measurements obtained before and 1 week into a 3-month adriamycin/cytoxan neoadjuvant chemotherapy regimen can predict final, postsurgical pathological response. Baseline DOS measurements of 11 patients before therapy revealed significant increases in tumor ctHHb, ctO(2)Hb, ctH(2)O, and spectral scattering slope, and decreases in bulk lipids, relative to normal breast tissue. Tumor concentrations of ctHHb, ctO(2)Hb, and ctH(2)O dropped 27 +/- 15%, 33 +/- 7%, and 11 +/- 15%, respectively, within 1 week (6.5 +/- 1.4 days) of the first treatment for pathology-confirmed responders (n = 6), whereas nonresponders (n = 5) and normal side controls showed no significant changes in these parameters. The best single predictor of therapeutic response 1 week posttreatment was ctHHb (83% sensitivity, 100% specificity), while discrimination analysis based on combined ctHHb and ctH(2)O changes classified responders vs. nonresponders with 100% sensitivity and specificity. In addition, the pretreatment tumor-to-normal ctO(2)Hb ratio was significantly higher in responders (2.82 +/- 0.44) vs. nonresponders (1.82 +/- 0.49). These results highlight DOS sensitivity to tumor cellular metabolism and biochemical composition and demonstrate its potential for predicting and monitoring an individual's response to treatment.

Current Trends and Controversies over Pre-operative Chemotherapy for Women with Operable Breast Cancer

The multi-disciplinary approach, including surgery, chemotherapy, endocrine therapy and radiation therapy, has become the standard treatment for primary breast cancer patients. The indication of pre-operative chemotherapy has been extended to women with potentially operable breast cancer based on the results of large randomized studies and has become an attractive option that extends the chance of breast conservation. The clinical and pathological responses to pre-operative chemotherapy correlates with long-term outcome. The anthracycline-containing regimen is now considered the standard. Sequential administration of non-cross-resistant drugs, namely taxanes, improves local tumor response but its long-term benefit has been controversial. Prediction of response to pre-operative chemotherapy still remains a challenge. Identification of useful predictive markers and development of molecular-targeted drugs is the key to individualized therapy in the future.

Monitoring of early response to neoadjuvant chemotherapy in stage II and III breast cancer by [18F]fluorodeoxyglucose positron emission tomography

PURPOSE

This study aimed to assess prospectively the efficacy of sequential [18F]fluorodeoxyglucose positron emission tomography (FDG PET) to evaluate early response to neoadjuvant chemotherapy in stage II and III breast cancer patients.

PATIENTS AND METHODS

Images were acquired with a PET/computed tomography scanner in 64 patients after administration of FDG (5 MBq/kg) at baseline and after the first, second, third, and sixth course of chemotherapy. Ultrasound and mammography were used to assess tumor size. Decrease in the standardized uptake value (SUV) with PET was compared with the pathologic response.

RESULTS

Surgery was performed after six courses of chemotherapy and pathologic analysis revealed gross residual disease in 28 patients and minimal residual disease in 36 patients. Although SUV data did not vary much in nonresponders (based on pathology findings), they decreased markedly to background levels in 94% (34 of 36) of responders. When using 60% of SUV at baseline as the cutoff value, the sensitivity, specificity, and negative predictive value of FDG PET were 61%, 96%, and 68% after one course of chemotherapy, 89%, 95%, and 85% after two courses, and 88%, 73%, and 83% after three courses, respectively. The same parameters with ultrasound (US) and mammography were 64%, 43%, and 55%, and 31%, 56%, and 45%, respectively. Assessment of tumor response with US or mammography was never significant whatever the cutoff.

CONCLUSION

Pathologic response to neoadjuvant chemotherapy in stage II and III breast cancer can be predicted accurately by FDG PET after two courses of chemotherapy.

Monitoring primary breast cancer throughout chemotherapy using FDG-PET

We have compared 2-deoxy-2-[(18)F]-fluoro-D-glucose positron emission tomography (FDG-PET) images of large or locally advanced breast cancers (LABC) acquired during Anthracycline-based chemotherapy. The purpose was to determine whether there is an optimal method for defining tumour volume and an optimal imaging time for predicting pathologic chemotherapy response.

METHOD

PET data were acquired before the first and second cycles, at the midpoint and at the endpoint of neoadjuvant chemotherapy. FDG uptake was quantified using the mean and maximum standardized uptake values (SUV) and the coefficient of variation within a region of interest. Receiver-operator characteristic (ROC) analysis was used to determine the discrimination between tumours demonstrating a high pathological response (i.e. those with greater than 90% reduction in viable tumour cells) and low pathological response.

RESULTS

Only tumours with an initial tumour to background ratio (TBR) of greater than five showed a difference between response categories. In terms of response discrimination, there was no statistically significant advantage of any of the methods used for image quantification or any of the time points. The best discrimination was measured for mean SUV at the midpoint of therapy, which identified 77% of low responding tumours whilst correctly identifying 100% of high responding tumours and had an ROC area of 0.93.

CONCLUSION

FDG-PET is efficacious for predicting the pathologic response of most primary breast tumours throughout the duration of a neoadjuvant chemotherapy regimen. However, this technique is ineffective for tumours with low image contrast on pre-therapy PET scans.

Multicellular tumour spheroid as a model for evaluation of [18F]FDG as biomarker for breast cancer treatment monitoring

Background

In order to explore a pre-clinical method to evaluate if [¹⁸F]FDG is valid for monitoring early response, we investigated the uptake of FDG in Multicellular tumour spheroids (MTS) without and with treatment with five routinely used chemotherapy agents in breast cancer.

Methods

The response to each anticancer treatment was evaluated by measurement of the [¹⁸F]FDG uptake and viable volume of the MTSs after 2 and 3 days of treatment.

Results

The effect of Paclitaxel and Docetaxel on [¹⁸F]FDG uptake per viable volume was more evident in BT474 (up to 55% decrease) than in MCF-7 (up to 25% decrease).

Doxorubicin reduced the [¹⁸F]FDG uptake per viable volume more noticeable in MCF-7 (25%) than in BT474 MTSs.

Tamoxifen reduced the [¹⁸F]FDG uptake per viable volume only in MCF-7 at the highest dose of 1 μM.

No effect of Imatinib was observed.

Conclusion

MTS was shown to be appropriate to investigate the potential of FDG-PET for early breast cancer treatment monitoring; the treatment effect can be observed before any tumour size changes occur.

The combination of PET radiotracers and image analysis in MTS provides a good model to evaluate the relationship between tumour volume and the uptake of metabolic tracer before and after chemotherapy. This feature could be used for screening and selecting PET-tracers for early assessment of treatment response.

In addition, this new method gives a possibility to assess quickly, and in vitro, a good preclinical profile of existing and newly developed anti-cancer drugs.